<?xml version="1.0" encoding="UTF-8"?>
<dataset name="isotopes" title="Isotopes of the chemical elements" source="https://aidb.si/d/isotopes">
  <row>
    <isotope>H-1</isotope>
    <atomic_number>1</atomic_number>
    <element_symbol>H</element_symbol>
    <nist_symbol>H</nist_symbol>
    <mass_number>1</mass_number>
    <neutrons>0</neutrons>
    <relative_atomic_mass>1.00782503223</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9e-11</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.999885</natural_abundance>
    <natural_abundance_uncertainty>0.00007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[1.00784,1.00811]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>H-2</isotope>
    <atomic_number>1</atomic_number>
    <element_symbol>H</element_symbol>
    <nist_symbol>D</nist_symbol>
    <mass_number>2</mass_number>
    <neutrons>1</neutrons>
    <relative_atomic_mass>2.01410177812</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.2e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.000115</natural_abundance>
    <natural_abundance_uncertainty>0.00007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[1.00784,1.00811]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>H-3</isotope>
    <atomic_number>1</atomic_number>
    <element_symbol>H</element_symbol>
    <nist_symbol>T</nist_symbol>
    <mass_number>3</mass_number>
    <neutrons>2</neutrons>
    <relative_atomic_mass>3.0160492779</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.4e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[1.00784,1.00811]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>H-4</isotope>
    <atomic_number>1</atomic_number>
    <element_symbol>H</element_symbol>
    <nist_symbol>H</nist_symbol>
    <mass_number>4</mass_number>
    <neutrons>3</neutrons>
    <relative_atomic_mass>4.02643</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[1.00784,1.00811]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>H-5</isotope>
    <atomic_number>1</atomic_number>
    <element_symbol>H</element_symbol>
    <nist_symbol>H</nist_symbol>
    <mass_number>5</mass_number>
    <neutrons>4</neutrons>
    <relative_atomic_mass>5.035311</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000096</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[1.00784,1.00811]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>H-6</isotope>
    <atomic_number>1</atomic_number>
    <element_symbol>H</element_symbol>
    <nist_symbol>H</nist_symbol>
    <mass_number>6</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>6.04496</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[1.00784,1.00811]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>H-7</isotope>
    <atomic_number>1</atomic_number>
    <element_symbol>H</element_symbol>
    <nist_symbol>H</nist_symbol>
    <mass_number>7</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>7.0527</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[1.00784,1.00811]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>He-3</isotope>
    <atomic_number>2</atomic_number>
    <element_symbol>He</element_symbol>
    <nist_symbol>He</nist_symbol>
    <mass_number>3</mass_number>
    <neutrons>1</neutrons>
    <relative_atomic_mass>3.0160293201</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.5e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00000134</natural_abundance>
    <natural_abundance_uncertainty>3e-8</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>4.002602(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>He-4</isotope>
    <atomic_number>2</atomic_number>
    <element_symbol>He</element_symbol>
    <nist_symbol>He</nist_symbol>
    <mass_number>4</mass_number>
    <neutrons>2</neutrons>
    <relative_atomic_mass>4.00260325413</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6e-11</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.99999866</natural_abundance>
    <natural_abundance_uncertainty>3e-8</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>4.002602(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>He-5</isotope>
    <atomic_number>2</atomic_number>
    <element_symbol>He</element_symbol>
    <nist_symbol>He</nist_symbol>
    <mass_number>5</mass_number>
    <neutrons>3</neutrons>
    <relative_atomic_mass>5.012057</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>4.002602(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>He-6</isotope>
    <atomic_number>2</atomic_number>
    <element_symbol>He</element_symbol>
    <nist_symbol>He</nist_symbol>
    <mass_number>6</mass_number>
    <neutrons>4</neutrons>
    <relative_atomic_mass>6.018885891</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.7e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>4.002602(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>He-7</isotope>
    <atomic_number>2</atomic_number>
    <element_symbol>He</element_symbol>
    <nist_symbol>He</nist_symbol>
    <mass_number>7</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>7.0279907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>4.002602(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>He-8</isotope>
    <atomic_number>2</atomic_number>
    <element_symbol>He</element_symbol>
    <nist_symbol>He</nist_symbol>
    <mass_number>8</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>8.03393439</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>4.002602(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>He-9</isotope>
    <atomic_number>2</atomic_number>
    <element_symbol>He</element_symbol>
    <nist_symbol>He</nist_symbol>
    <mass_number>9</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>9.043946</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>4.002602(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>He-10</isotope>
    <atomic_number>2</atomic_number>
    <element_symbol>He</element_symbol>
    <nist_symbol>He</nist_symbol>
    <mass_number>10</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>10.05279</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>4.002602(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Li-3</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>3</mass_number>
    <neutrons>0</neutrons>
    <relative_atomic_mass>3.0308</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-4</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>4</mass_number>
    <neutrons>1</neutrons>
    <relative_atomic_mass>4.02719</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-5</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>5</mass_number>
    <neutrons>2</neutrons>
    <relative_atomic_mass>5.012538</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-6</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>6</mass_number>
    <neutrons>3</neutrons>
    <relative_atomic_mass>6.0151228874</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.6e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0759</natural_abundance>
    <natural_abundance_uncertainty>0.0004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-7</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>7</mass_number>
    <neutrons>4</neutrons>
    <relative_atomic_mass>7.0160034366</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.5e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.9241</natural_abundance>
    <natural_abundance_uncertainty>0.0004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-8</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>8</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>8.022486246</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-9</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>9</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>9.02679019</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-10</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>10</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>10.035483</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-11</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>11</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>11.04372358</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-12</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>12</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>12.052517</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Li-13</isotope>
    <atomic_number>3</atomic_number>
    <element_symbol>Li</element_symbol>
    <nist_symbol>Li</nist_symbol>
    <mass_number>13</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>13.06263</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[6.938,6.997]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Be-5</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>5</mass_number>
    <neutrons>1</neutrons>
    <relative_atomic_mass>5.0399</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-6</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>6</mass_number>
    <neutrons>2</neutrons>
    <relative_atomic_mass>6.0197264</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-7</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>7</mass_number>
    <neutrons>3</neutrons>
    <relative_atomic_mass>7.016928717</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.6e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-8</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>8</mass_number>
    <neutrons>4</neutrons>
    <relative_atomic_mass>8.005305102</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.7e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-9</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>9</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>9.012183065</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.2e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-10</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>10</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>10.013534695</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.6e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-11</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>11</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>11.02166108</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-12</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>12</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>12.0269221</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-13</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>13</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>13.036135</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-14</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>14</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>14.04289</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-15</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>15</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>15.05342</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Be-16</isotope>
    <atomic_number>4</atomic_number>
    <element_symbol>Be</element_symbol>
    <nist_symbol>Be</nist_symbol>
    <mass_number>16</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>16.06167</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>9.0121831(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>B-6</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>6</mass_number>
    <neutrons>1</neutrons>
    <relative_atomic_mass>6.0508</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-7</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>7</mass_number>
    <neutrons>2</neutrons>
    <relative_atomic_mass>7.029712</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-8</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>8</mass_number>
    <neutrons>3</neutrons>
    <relative_atomic_mass>8.0246073</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-9</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>9</mass_number>
    <neutrons>4</neutrons>
    <relative_atomic_mass>9.01332965</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-10</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>10</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>10.01293695</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.199</natural_abundance>
    <natural_abundance_uncertainty>0.007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-11</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>11</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>11.00930536</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.801</natural_abundance>
    <natural_abundance_uncertainty>0.007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-12</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>12</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>12.0143527</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-13</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>13</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>13.0177802</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-14</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>14</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>14.025404</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-15</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>15</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>15.031088</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-16</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>16</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>16.039842</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-17</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>17</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>17.04699</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-18</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>18</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>18.05566</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-19</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>19</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>19.0631</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-20</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>20</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>20.07207</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>B-21</isotope>
    <atomic_number>5</atomic_number>
    <element_symbol>B</element_symbol>
    <nist_symbol>B</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>21.08129</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00097</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[10.806,10.821]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>C-8</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>8</mass_number>
    <neutrons>2</neutrons>
    <relative_atomic_mass>8.037643</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-9</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>9</mass_number>
    <neutrons>3</neutrons>
    <relative_atomic_mass>9.0310372</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-10</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>10</mass_number>
    <neutrons>4</neutrons>
    <relative_atomic_mass>10.01685331</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-11</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>11</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>11.0114336</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-12</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>12</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>12</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.9893</natural_abundance>
    <natural_abundance_uncertainty>0.0008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-13</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>13</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>13.00335483507</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.3e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0107</natural_abundance>
    <natural_abundance_uncertainty>0.0008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-14</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>14</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>14.0032419884</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-15</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>15</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>15.01059926</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-16</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>16</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>16.0147013</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-17</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>17</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>17.022577</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-18</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>18</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>18.026751</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-19</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>19</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>19.0348</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-20</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>20</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>20.04032</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-21</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>21.049</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-22</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>22.05753</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>C-23</isotope>
    <atomic_number>6</atomic_number>
    <element_symbol>C</element_symbol>
    <nist_symbol>C</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>23.0689</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[12.0096,12.0116]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-10</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>10</mass_number>
    <neutrons>3</neutrons>
    <relative_atomic_mass>10.04165</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-11</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>11</mass_number>
    <neutrons>4</neutrons>
    <relative_atomic_mass>11.026091</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-12</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>12</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>12.0186132</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-13</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>13</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>13.00573861</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-14</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>14</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>14.00307400443</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.99636</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-15</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>15</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>15.00010889888</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.4e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00364</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-16</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>16</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>16.0061019</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-17</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>17</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>17.008449</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-18</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>18</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>18.014078</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-19</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>19</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>19.017022</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-20</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>20</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>20.023366</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00006</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-21</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>21.02711</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-22</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>22.03439</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-23</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>23.04114</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-24</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>24.05039</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>N-25</isotope>
    <atomic_number>7</atomic_number>
    <element_symbol>N</element_symbol>
    <nist_symbol>N</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>25.0601</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[14.00643,14.00728]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-12</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>12</mass_number>
    <neutrons>4</neutrons>
    <relative_atomic_mass>12.034262</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-13</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>13</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>13.024815</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-14</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>14</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>14.00859636</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-15</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>15</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>15.00306562</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-16</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>16</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>15.99491461957</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.7e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.99757</natural_abundance>
    <natural_abundance_uncertainty>0.00016</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-17</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>17</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>16.9991317565</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.9e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00038</natural_abundance>
    <natural_abundance_uncertainty>0.00001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-18</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>18</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>17.99915961286</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.6e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00205</natural_abundance>
    <natural_abundance_uncertainty>0.00014</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-19</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>19</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>19.003578</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-20</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>20</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>20.00407535</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-21</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>21.008655</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-22</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>22.009966</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-23</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>23.015696</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000097</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-24</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>24.01986</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-25</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>25.02936</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-26</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>26.03729</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-27</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>27.04772</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>O-28</isotope>
    <atomic_number>8</atomic_number>
    <element_symbol>O</element_symbol>
    <nist_symbol>O</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>28.05591</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[15.99903,15.99977]</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-14</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>14</mass_number>
    <neutrons>5</neutrons>
    <relative_atomic_mass>14.034315</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-15</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>15</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>15.018043</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-16</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>16</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>16.0114657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-17</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>17</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>17.00209524</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-18</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>18</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>18.00093733</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-19</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>19</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>18.99840316273</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.2e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-20</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>20</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>19.999981252</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.1e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-21</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>20.9999489</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-22</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>22.002999</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-23</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>23.003557</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-24</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>24.008115</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-25</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>25.012199</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-26</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>26.020038</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000083</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-27</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>27.02644</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-28</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>28.03534</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-29</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>29.04254</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-30</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>30.05165</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>F-31</isotope>
    <atomic_number>9</atomic_number>
    <element_symbol>F</element_symbol>
    <nist_symbol>F</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>31.05971</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00056</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>18.998403163(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ne-16</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>16</mass_number>
    <neutrons>6</neutrons>
    <relative_atomic_mass>16.02575</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-17</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>17</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>17.01771396</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-18</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>18</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>18.0057087</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-19</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>19</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>19.00188091</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-20</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>20</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>19.9924401762</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.7e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.9048</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-21</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>20.993846685</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.1e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0027</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-22</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>21.991385114</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.8e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0925</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-23</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>22.99446691</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-24</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>23.99361065</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-25</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>24.997789</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-26</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>26.000515</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-27</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>27.007553</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00007</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-28</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>28.01212</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-29</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>29.01975</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-30</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>30.02473</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-31</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>31.0331</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-32</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>32.03972</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-33</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>33.04938</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ne-34</isotope>
    <atomic_number>10</atomic_number>
    <element_symbol>Ne</element_symbol>
    <nist_symbol>Ne</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>34.05673</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00055</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>20.1797(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Na-18</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>18</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>18.02688</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-19</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>19</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>19.01388</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-20</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>20</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>20.0073544</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-21</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>20.99765469</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-22</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>21.99443741</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-23</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>22.989769282</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.9e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-24</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>23.99096295</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.8e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-25</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>24.989954</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-26</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>25.9926346</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-27</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>26.9940765</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-28</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>27.998939</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-29</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>29.0028771</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-30</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>30.0090979</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-31</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>31.013163</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-32</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>32.02019</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-33</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>33.02573</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-34</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>34.03359</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-35</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>35.04062</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00063</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-36</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>36.04929</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Na-37</isotope>
    <atomic_number>11</atomic_number>
    <element_symbol>Na</element_symbol>
    <nist_symbol>Na</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>37.05705</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00065</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>22.98976928(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-19</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>19</mass_number>
    <neutrons>7</neutrons>
    <relative_atomic_mass>19.034169</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-20</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>20</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>20.01885</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-21</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>21.011716</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-22</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>21.99957065</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-23</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>22.99412421</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-24</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>23.985041697</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.4e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.7899</natural_abundance>
    <natural_abundance_uncertainty>0.0004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-25</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>24.985836976</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-26</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>25.982592968</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.1e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1101</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-27</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>26.984340624</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.3e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-28</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>27.9838767</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-29</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>28.988617</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-30</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>29.9904629</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-31</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>30.996648</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-32</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>31.9991102</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-33</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>33.0053271</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-34</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>34.008935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-35</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>35.01679</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-36</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>36.02188</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-37</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>37.03037</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-38</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>38.03658</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-39</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>39.04538</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00055</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mg-40</isotope>
    <atomic_number>12</atomic_number>
    <element_symbol>Mg</element_symbol>
    <nist_symbol>Mg</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>40.05218</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[24.304,24.307]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-21</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>21</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>21.02897</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-22</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>22.01954</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-23</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>23.00724435</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-24</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>23.9999489</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-25</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>24.9904281</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-26</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>25.986891904</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.9e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-27</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>26.98153853</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-28</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>27.98191021</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-29</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>28.9804565</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-30</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>29.98296</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-31</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>30.983945</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-32</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>31.988085</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-33</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>32.990909</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-34</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>33.996705</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000074</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-35</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>34.999764</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-36</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>36.00639</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-37</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>37.01053</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-38</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>38.0174</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-39</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>39.02254</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-40</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>40.03003</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-41</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>41.03638</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-42</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>42.04384</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Al-43</isotope>
    <atomic_number>13</atomic_number>
    <element_symbol>Al</element_symbol>
    <nist_symbol>Al</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>43.05147</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>26.9815385(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-22</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>22</mass_number>
    <neutrons>8</neutrons>
    <relative_atomic_mass>22.03579</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-23</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>23</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>23.02544</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-24</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>24.011535</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-25</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>25.004109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-26</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>25.99233384</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-27</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>26.98670481</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-28</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>27.97692653465</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.4e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.92223</natural_abundance>
    <natural_abundance_uncertainty>0.00019</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-29</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>28.9764946649</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.04685</natural_abundance>
    <natural_abundance_uncertainty>0.00008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-30</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>29.973770136</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.3e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.03092</natural_abundance>
    <natural_abundance_uncertainty>0.00011</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-31</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>30.975363194</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.6e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-32</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>31.97415154</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-33</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>32.97797696</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-34</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>33.978576</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-35</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>34.984583</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-36</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>35.986695</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-37</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>36.992921</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-38</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>37.995523</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-39</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>39.002491</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000097</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-40</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>40.00583</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-41</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>41.01301</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-42</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>42.01778</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-43</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>43.0248</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-44</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>44.03061</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Si-45</isotope>
    <atomic_number>14</atomic_number>
    <element_symbol>Si</element_symbol>
    <nist_symbol>Si</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>45.03995</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[28.084,28.086]</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-24</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>24</mass_number>
    <neutrons>9</neutrons>
    <relative_atomic_mass>24.03577</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-25</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>25</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>25.02119</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-26</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>26.01178</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-27</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>26.999224</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-28</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>27.9923266</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-29</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>28.98180079</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-30</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>29.97831375</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-31</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>30.97376199842</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7e-10</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-32</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>31.973907643</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.2e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-33</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>32.9717257</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-34</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>33.97364589</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-35</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>34.9733141</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-36</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>35.97826</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-37</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>36.979607</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-38</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>37.984252</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-39</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>38.986227</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-40</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>39.99133</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-41</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>40.994654</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-42</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>42.00108</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-43</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>43.00502</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-44</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>44.01121</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-45</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>45.01645</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-46</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>46.02446</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>P-47</isotope>
    <atomic_number>15</atomic_number>
    <element_symbol>P</element_symbol>
    <nist_symbol>P</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>47.03139</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>30.973761998(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-26</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>26</mass_number>
    <neutrons>10</neutrons>
    <relative_atomic_mass>26.02907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-27</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>27</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>27.01828</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-28</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>28.00437</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-29</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>28.996611</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-30</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>29.98490703</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-31</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>30.97955701</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-32</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>31.9720711744</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.4e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.9499</natural_abundance>
    <natural_abundance_uncertainty>0.0026</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-33</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>32.9714589098</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.5e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0075</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-34</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>33.967867004</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.7e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0425</natural_abundance>
    <natural_abundance_uncertainty>0.0024</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-35</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>34.96903231</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.3e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-36</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>35.96708071</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0001</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-37</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>36.97112551</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-38</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>37.9711633</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-39</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>38.975134</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-40</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>39.9754826</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-41</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>40.9795935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-42</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>41.9810651</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-43</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>42.9869076</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-44</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>43.9901188</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-45</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>44.99572</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00074</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-46</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>46.00004</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-47</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>47.00795</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-48</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>48.0137</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>S-49</isotope>
    <atomic_number>16</atomic_number>
    <element_symbol>S</element_symbol>
    <nist_symbol>S</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>49.02276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00072</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[32.059,32.076]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cl-28</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>28</mass_number>
    <neutrons>11</neutrons>
    <relative_atomic_mass>28.02954</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-29</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>29</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>29.01478</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-30</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>30.00477</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-31</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>30.992414</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-32</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>31.98568464</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-33</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>32.97745199</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-34</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>33.973762485</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-35</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>34.968852682</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.7e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.7576</natural_abundance>
    <natural_abundance_uncertainty>0.001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-36</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>35.968306809</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.8e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-37</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>36.965902602</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.5e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2424</natural_abundance>
    <natural_abundance_uncertainty>0.001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-38</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>37.96801044</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-39</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>38.9680082</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-40</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>39.970415</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-41</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>40.970685</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000074</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-42</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>41.97325</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-43</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>42.97389</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-44</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>43.97787</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-45</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>44.98029</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-46</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>45.98517</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-47</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>46.98916</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-48</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>47.99564</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-49</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>49.00123</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-50</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>50.00905</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cl-51</isotope>
    <atomic_number>17</atomic_number>
    <element_symbol>Cl</element_symbol>
    <nist_symbol>Cl</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>51.01554</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[35.446,35.457]</standard_atomic_weight>
    <notes>m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Ar-30</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>30</mass_number>
    <neutrons>12</neutrons>
    <relative_atomic_mass>30.02307</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-31</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>31</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>31.01212</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-32</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>31.9976378</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-33</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>32.98992555</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-34</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>33.98027009</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.3e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-35</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>34.97525759</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-36</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>35.967545105</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.8e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.003336</natural_abundance>
    <natural_abundance_uncertainty>0.000021</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-37</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>36.96677633</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-38</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>37.96273211</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.000629</natural_abundance>
    <natural_abundance_uncertainty>0.000007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-39</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>38.964313</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-40</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>39.9623831237</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.4e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.996035</natural_abundance>
    <natural_abundance_uncertainty>0.000025</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-41</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>40.96450057</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-42</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>41.9630457</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-43</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>42.9656361</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-44</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>43.9649238</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-45</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>44.96803973</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-46</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>45.968083</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-47</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>46.972935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000096</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-48</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>47.97591</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-49</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>48.9819</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-50</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>49.98613</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-51</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>50.9937</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-52</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>51.99896</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ar-53</isotope>
    <atomic_number>18</atomic_number>
    <element_symbol>Ar</element_symbol>
    <nist_symbol>Ar</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>53.00729</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.948(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>K-32</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>32</mass_number>
    <neutrons>13</neutrons>
    <relative_atomic_mass>32.02265</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-33</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>33</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>33.00756</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-34</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>33.99869</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-35</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>34.98800541</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-36</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>35.98130201</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-37</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>36.97337589</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-38</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>37.96908112</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-39</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>38.9637064864</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.9e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.932581</natural_abundance>
    <natural_abundance_uncertainty>0.000044</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-40</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>39.963998166</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.000117</natural_abundance>
    <natural_abundance_uncertainty>0.000001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-41</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>40.9618252579</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.1e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.067302</natural_abundance>
    <natural_abundance_uncertainty>0.000044</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-42</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>41.96240231</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-43</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>42.9607347</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-44</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>43.96158699</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-45</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>44.96069149</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-46</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>45.96198159</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-47</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>46.9616616</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-48</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>47.96534119</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-49</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>48.96821075</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-50</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>49.97238</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000083</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-51</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>50.975828</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-52</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>51.98224</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-53</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>52.98746</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-54</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>53.99463</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-55</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>55.00076</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>K-56</isotope>
    <atomic_number>19</atomic_number>
    <element_symbol>K</element_symbol>
    <nist_symbol>K</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>56.00851</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>39.0983(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ca-34</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>34</mass_number>
    <neutrons>14</neutrons>
    <relative_atomic_mass>34.01487</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-35</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>35</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>35.00514</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-36</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>35.993074</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-37</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>36.98589785</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-38</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>37.97631922</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-39</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>38.97071081</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-40</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>39.962590863</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.2e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.96941</natural_abundance>
    <natural_abundance_uncertainty>0.00156</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-41</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>40.96227792</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-42</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>41.95861783</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00647</natural_abundance>
    <natural_abundance_uncertainty>0.00023</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-43</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>42.95876644</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00135</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-44</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>43.95548156</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.02086</natural_abundance>
    <natural_abundance_uncertainty>0.0011</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-45</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>44.95618635</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-46</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>45.953689</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00004</natural_abundance>
    <natural_abundance_uncertainty>0.00003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-47</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>46.9545424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-48</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>47.95252276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00187</natural_abundance>
    <natural_abundance_uncertainty>0.00021</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-49</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>48.95566274</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-50</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>49.9574992</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-51</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>50.960989</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-52</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>51.963217</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-53</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>52.96945</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-54</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>53.9734</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-55</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>54.9803</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-56</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>55.98508</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-57</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>56.99262</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ca-58</isotope>
    <atomic_number>20</atomic_number>
    <element_symbol>Ca</element_symbol>
    <nist_symbol>Ca</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>57.99794</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>40.078(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sc-36</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>36</mass_number>
    <neutrons>15</neutrons>
    <relative_atomic_mass>36.01648</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-37</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>37</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>37.00374</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-38</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>37.99512</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-39</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>38.984785</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-40</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>39.9779673</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-41</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>40.969251105</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.8e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-42</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>41.96551653</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-43</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>42.9611505</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-44</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>43.9594029</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-45</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>44.95590828</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-46</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>45.95516826</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-47</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>46.9524037</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-48</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>47.9522236</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-49</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>48.9500146</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-50</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>49.952176</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-51</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>50.953592</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-52</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>51.95688</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-53</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>52.95909</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-54</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>53.96393</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-55</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>54.96782</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-56</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>55.97345</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-57</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>56.97777</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-58</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>57.98403</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-59</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>58.98894</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-60</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>59.99565</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sc-61</isotope>
    <atomic_number>21</atomic_number>
    <element_symbol>Sc</element_symbol>
    <nist_symbol>Sc</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>61.001</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>44.955908(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-38</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>38</mass_number>
    <neutrons>16</neutrons>
    <relative_atomic_mass>38.01145</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-39</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>39</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>39.00236</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-40</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>39.9905</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-41</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>40.983148</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-42</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>41.97304903</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-43</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>42.9685225</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-44</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>43.95968995</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-45</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>44.95812198</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-46</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>45.95262772</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0825</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-47</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>46.95175879</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0744</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-48</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>47.94794198</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.7372</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-49</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>48.94786568</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0541</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-50</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>49.94478689</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0518</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-51</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>50.94661065</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-52</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>51.946893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-53</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>52.94973</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-54</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>53.95105</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-55</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>54.95527</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-56</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>55.95791</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-57</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>56.96364</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-58</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>57.9666</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-59</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>58.97247</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-60</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>59.97603</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-61</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>60.98245</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-62</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>61.98651</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ti-63</isotope>
    <atomic_number>22</atomic_number>
    <element_symbol>Ti</element_symbol>
    <nist_symbol>Ti</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>62.99375</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>47.867(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-40</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>40</mass_number>
    <neutrons>17</neutrons>
    <relative_atomic_mass>40.01276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-41</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>41</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>41.00021</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-42</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>41.99182</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-43</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>42.980766</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-44</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>43.97411</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-45</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>44.9657748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-46</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>45.96019878</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-47</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>46.95490491</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-48</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>47.9522522</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-49</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>48.9485118</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-50</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>49.94715601</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0025</natural_abundance>
    <natural_abundance_uncertainty>0.00004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-51</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>50.94395704</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.9975</natural_abundance>
    <natural_abundance_uncertainty>0.00004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-52</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>51.94477301</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-53</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>52.9443367</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-54</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>53.946439</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-55</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>54.94724</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-56</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>55.95048</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-57</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>56.95252</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-58</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>57.95672</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-59</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>58.95939</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-60</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>59.96431</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-61</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>60.96725</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00096</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-62</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>61.97265</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-63</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>62.97639</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-64</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>63.98264</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-65</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>64.9875</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>V-66</isotope>
    <atomic_number>23</atomic_number>
    <element_symbol>V</element_symbol>
    <nist_symbol>V</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>65.99398</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>50.9415(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-42</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>42</mass_number>
    <neutrons>18</neutrons>
    <relative_atomic_mass>42.0067</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-43</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>43</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>42.99753</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-44</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>43.98536</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-45</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>44.97905</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-46</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>45.968359</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-47</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>46.9628974</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-48</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>47.9540291</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-49</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>48.9513333</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-50</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>49.94604183</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.04345</natural_abundance>
    <natural_abundance_uncertainty>0.00013</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-51</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>50.94476502</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-52</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>51.94050623</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.83789</natural_abundance>
    <natural_abundance_uncertainty>0.00018</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-53</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>52.94064815</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.09501</natural_abundance>
    <natural_abundance_uncertainty>0.00017</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-54</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>53.93887916</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.02365</natural_abundance>
    <natural_abundance_uncertainty>0.00007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-55</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>54.94083843</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-56</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>55.9406531</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-57</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>56.943613</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-58</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>57.94435</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-59</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>58.94859</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-60</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>59.95008</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-61</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>60.95442</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-62</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>61.9561</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-63</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>62.96165</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-64</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>63.96408</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-65</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>64.96996</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-66</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>65.97366</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-67</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>66.98016</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cr-68</isotope>
    <atomic_number>24</atomic_number>
    <element_symbol>Cr</element_symbol>
    <nist_symbol>Cr</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>67.98403</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>51.9961(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-44</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>44</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>44.00715</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-45</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>44.99449</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-46</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>45.98609</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-47</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>46.975775</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-48</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>47.96852</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-49</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>48.959595</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-50</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>49.95423778</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-51</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>50.94820847</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-52</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>51.9455639</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-53</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>52.94128889</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-54</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>53.9403576</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-55</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>54.93804391</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-56</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>55.93890369</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-57</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>56.9382861</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-58</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>57.9400666</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-59</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>58.9403911</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-60</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>59.9431366</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-61</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>60.9444525</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-62</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>61.94795</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-63</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>62.9496647</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-64</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>63.9538494</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-65</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>64.9560198</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-66</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>65.960547</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-67</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>66.96424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-68</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>67.96962</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-69</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>68.97366</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-70</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>69.97937</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mn-71</isotope>
    <atomic_number>25</atomic_number>
    <element_symbol>Mn</element_symbol>
    <nist_symbol>Mn</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>70.98368</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>54.938044(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-45</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>45</mass_number>
    <neutrons>19</neutrons>
    <relative_atomic_mass>45.01442</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-46</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>46</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>46.00063</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-47</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>46.99185</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-48</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>47.98023</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-49</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>48.973429</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-50</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>49.962975</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-51</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>50.956841</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000096</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-52</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>51.9481131</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000007</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-53</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>52.9453064</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-54</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>53.93960899</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.05845</natural_abundance>
    <natural_abundance_uncertainty>0.00035</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-55</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>54.93829199</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-56</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>55.93493633</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.91754</natural_abundance>
    <natural_abundance_uncertainty>0.00036</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-57</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>56.93539284</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.02119</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-58</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>57.93327443</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00282</natural_abundance>
    <natural_abundance_uncertainty>0.00004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-59</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>58.93487434</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-60</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>59.9340711</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-61</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>60.9367462</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-62</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>61.9367918</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-63</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>62.9402727</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-64</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>63.9409878</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-65</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>64.9450115</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-66</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>65.94625</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-67</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>66.95054</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-68</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>67.95295</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-69</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>68.95807</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-70</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>69.96102</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-71</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>70.96672</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-72</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>71.96983</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-73</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>72.97572</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Fe-74</isotope>
    <atomic_number>26</atomic_number>
    <element_symbol>Fe</element_symbol>
    <nist_symbol>Fe</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>73.97935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>55.845(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-47</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>47</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>47.01057</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-48</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>48.00093</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-49</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>48.98891</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-50</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>49.98091</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-51</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>50.970647</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000052</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-52</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>51.96351</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-53</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>52.9542041</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-54</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>53.94845987</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-55</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>54.9419972</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-56</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>55.9398388</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-57</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>56.93629057</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-58</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>57.9357521</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-59</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>58.93319429</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-60</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>59.9338163</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-61</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>60.93247662</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-62</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>61.934059</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-63</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>62.9336</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-64</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>63.935811</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-65</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>64.9364621</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-66</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>65.939443</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-67</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>66.9406096</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-68</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>67.94426</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-69</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>68.94614</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-70</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>69.94963</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-71</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>70.95237</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-72</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>71.95729</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-73</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>72.96039</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-74</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>73.96515</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-75</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>74.96876</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Co-76</isotope>
    <atomic_number>27</atomic_number>
    <element_symbol>Co</element_symbol>
    <nist_symbol>Co</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>75.97413</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.933194(4)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ni-48</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>48</mass_number>
    <neutrons>20</neutrons>
    <relative_atomic_mass>48.01769</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-49</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>49</mass_number>
    <neutrons>21</neutrons>
    <relative_atomic_mass>49.0077</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-50</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>50</mass_number>
    <neutrons>22</neutrons>
    <relative_atomic_mass>49.99474</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-51</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>51</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>50.98611</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-52</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>51.9748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-53</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>52.96819</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-54</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>53.957892</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-55</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>54.95133063</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-56</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>55.94212855</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-57</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>56.93979218</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-58</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>57.93534241</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.68077</natural_abundance>
    <natural_abundance_uncertainty>0.00019</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-59</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>58.9343462</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-60</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>59.93078588</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.26223</natural_abundance>
    <natural_abundance_uncertainty>0.00015</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-61</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>60.93105557</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.011399</natural_abundance>
    <natural_abundance_uncertainty>0.000013</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-62</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>61.92834537</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.036346</natural_abundance>
    <natural_abundance_uncertainty>0.00004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-63</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>62.92966963</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-64</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>63.92796682</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.009255</natural_abundance>
    <natural_abundance_uncertainty>0.000019</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-65</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>64.93008517</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-66</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>65.9291393</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-67</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>66.9315694</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-68</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>67.9318688</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-69</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>68.9356103</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-70</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>69.9364313</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-71</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>70.940519</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-72</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>71.9417859</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-73</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>72.9462067</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-74</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>73.94798</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-75</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>74.9525</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-76</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>75.95533</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-77</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>76.96055</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-78</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>77.96336</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ni-79</isotope>
    <atomic_number>28</atomic_number>
    <element_symbol>Ni</element_symbol>
    <nist_symbol>Ni</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>78.97025</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>58.6934(4)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-52</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>52</mass_number>
    <neutrons>23</neutrons>
    <relative_atomic_mass>51.99671</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-53</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>53</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>52.98459</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-54</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>53.97666</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-55</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>54.96604</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-56</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>55.95895</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-57</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>56.9492125</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-58</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>57.94453305</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-59</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>58.93949748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-60</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>59.9373645</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-61</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>60.9334576</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-62</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>61.93259541</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-63</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>62.92959772</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.6915</natural_abundance>
    <natural_abundance_uncertainty>0.0015</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-64</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>63.92976434</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-65</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>64.9277897</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.3085</natural_abundance>
    <natural_abundance_uncertainty>0.0015</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-66</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>65.92886903</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-67</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>66.9277303</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-68</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>67.9296109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-69</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>68.9294293</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-70</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>69.9323921</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-71</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>70.9326768</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-72</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>71.9358203</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-73</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>72.9366744</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-74</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>73.9398749</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000066</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-75</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>74.9415226</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-76</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>75.945275</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-77</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>76.94792</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-78</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>77.95223</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-79</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>78.95502</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-80</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>79.96089</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-81</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>80.96587</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Cu-82</isotope>
    <atomic_number>29</atomic_number>
    <element_symbol>Cu</element_symbol>
    <nist_symbol>Cu</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>81.97244</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>63.546(3)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-54</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>54</mass_number>
    <neutrons>24</neutrons>
    <relative_atomic_mass>53.99204</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-55</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>55</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>54.98398</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-56</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>55.97254</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-57</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>56.96506</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-58</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>57.954591</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-59</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>58.94931266</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-60</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>59.9418421</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-61</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>60.939507</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-62</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>61.93433397</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-63</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>62.9332115</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-64</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>63.92914201</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.4917</natural_abundance>
    <natural_abundance_uncertainty>0.0075</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-65</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>64.92924077</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-66</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>65.92603381</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2773</natural_abundance>
    <natural_abundance_uncertainty>0.0098</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-67</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>66.92712775</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0404</natural_abundance>
    <natural_abundance_uncertainty>0.0016</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-68</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>67.92484455</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1845</natural_abundance>
    <natural_abundance_uncertainty>0.0063</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-69</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>68.9265507</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-70</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>69.9253192</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0061</natural_abundance>
    <natural_abundance_uncertainty>0.001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-71</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>70.9277196</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-72</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>71.9268428</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-73</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>72.9295826</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-74</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>73.9294073</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-75</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>74.9328402</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-76</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>75.933115</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-77</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>76.9368872</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-78</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>77.9382892</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-79</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>78.9426381</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-80</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>79.9445529</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-81</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>80.9504026</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-82</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>81.95426</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-83</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>82.96056</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-84</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>83.96521</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Zn-85</isotope>
    <atomic_number>30</atomic_number>
    <element_symbol>Zn</element_symbol>
    <nist_symbol>Zn</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>84.97226</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>65.38(2)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Ga-56</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>56</mass_number>
    <neutrons>25</neutrons>
    <relative_atomic_mass>55.99536</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-57</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>57</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>56.9832</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-58</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>57.97478</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-59</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>58.96353</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-60</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>59.95729</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-61</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>60.949399</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-62</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>61.94419025</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-63</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>62.9392942</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-64</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>63.9368404</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-65</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>64.93273459</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-66</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>65.9315894</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-67</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>66.9282025</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-68</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>67.9279805</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-69</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>68.9255735</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.60108</natural_abundance>
    <natural_abundance_uncertainty>0.00009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-70</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>69.9260219</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-71</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>70.92470258</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.39892</natural_abundance>
    <natural_abundance_uncertainty>0.00009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-72</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>71.92636747</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-73</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>72.9251747</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-74</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>73.9269457</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-75</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>74.9265002</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-76</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>75.9288276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-77</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>76.9291543</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-78</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>77.9316088</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-79</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>78.9328523</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-80</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>79.9364208</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-81</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>80.9381338</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-82</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>81.9431765</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-83</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>82.9471203</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-84</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>83.95246</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-85</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>84.95699</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-86</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>85.96301</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ga-87</isotope>
    <atomic_number>31</atomic_number>
    <element_symbol>Ga</element_symbol>
    <nist_symbol>Ga</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>86.96824</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>69.723(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-58</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>58</mass_number>
    <neutrons>26</neutrons>
    <relative_atomic_mass>57.99172</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-59</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>59</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>58.98249</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-60</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>59.97036</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-61</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>60.96379</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-62</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>61.95502</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-63</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>62.949628</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-64</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>63.9416899</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-65</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>64.9393681</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-66</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>65.9338621</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-67</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>66.9327339</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-68</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>67.9280953</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-69</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>68.9279645</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-70</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>69.92424875</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2057</natural_abundance>
    <natural_abundance_uncertainty>0.0027</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-71</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>70.92495233</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-72</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>71.922075826</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.1e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2745</natural_abundance>
    <natural_abundance_uncertainty>0.0032</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-73</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>72.923458956</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.1e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0775</natural_abundance>
    <natural_abundance_uncertainty>0.0012</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-74</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>73.921177761</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.3e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.365</natural_abundance>
    <natural_abundance_uncertainty>0.002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-75</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>74.92285837</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.5e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-76</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>75.921402726</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.9e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0773</natural_abundance>
    <natural_abundance_uncertainty>0.0012</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-77</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>76.923549843</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.7e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-78</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>77.9228529</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-79</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>78.92536</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-80</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>79.9253508</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-81</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>80.9288329</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-82</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>81.929774</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-83</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>82.9345391</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-84</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>83.9375751</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-85</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>84.9429697</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-86</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>85.94658</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-87</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>86.95268</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-88</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>87.95691</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-89</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>88.96379</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ge-90</isotope>
    <atomic_number>32</atomic_number>
    <element_symbol>Ge</element_symbol>
    <nist_symbol>Ge</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>89.96863</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>72.630(8)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-60</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>60</mass_number>
    <neutrons>27</neutrons>
    <relative_atomic_mass>59.99388</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-61</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>61</mass_number>
    <neutrons>28</neutrons>
    <relative_atomic_mass>60.98112</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-62</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>62</mass_number>
    <neutrons>29</neutrons>
    <relative_atomic_mass>61.97361</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-63</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>63</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>62.9639</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-64</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>63.95743</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-65</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>64.949611</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000091</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-66</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>65.9441488</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-67</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>66.93925111</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-68</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>67.9367741</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-69</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>68.932246</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-70</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>69.930926</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-71</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>70.9271138</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-72</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>71.9267523</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-73</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>72.9238291</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-74</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>73.9239286</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-75</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>74.92159457</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-76</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>75.92239202</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-77</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>76.9206476</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-78</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>77.921828</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-79</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>78.9209484</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-80</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>79.9224746</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-81</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>80.9221323</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-82</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>81.9247412</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-83</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>82.9252069</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-84</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>83.9293033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-85</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>84.9321637</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-86</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>85.9367015</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-87</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>86.9402917</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-88</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>87.94555</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-89</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>88.94976</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-90</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>89.95563</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-91</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>90.96039</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>As-92</isotope>
    <atomic_number>33</atomic_number>
    <element_symbol>As</element_symbol>
    <nist_symbol>As</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>91.96674</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>74.921595(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Se-64</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>64</mass_number>
    <neutrons>30</neutrons>
    <relative_atomic_mass>63.97109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-65</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>65</mass_number>
    <neutrons>31</neutrons>
    <relative_atomic_mass>64.9644</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-66</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>66</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>65.95559</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-67</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>66.949994</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-68</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>67.94182524</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-69</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>68.9394148</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-70</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>69.9335155</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-71</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>70.9322094</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-72</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>71.9271405</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-73</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>72.9267549</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-74</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>73.922475934</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.5e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0089</natural_abundance>
    <natural_abundance_uncertainty>0.0004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-75</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>74.92252287</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.8e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-76</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>75.919213704</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.7e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0937</natural_abundance>
    <natural_abundance_uncertainty>0.0029</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-77</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>76.919914154</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.7e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0763</natural_abundance>
    <natural_abundance_uncertainty>0.0016</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-78</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>77.91730928</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2377</natural_abundance>
    <natural_abundance_uncertainty>0.0028</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-79</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>78.91849929</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-80</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>79.9165218</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.4961</natural_abundance>
    <natural_abundance_uncertainty>0.0041</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-81</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>80.917993</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-82</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>81.9166995</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0873</natural_abundance>
    <natural_abundance_uncertainty>0.0022</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-83</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>82.9191186</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-84</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>83.9184668</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-85</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>84.9222608</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-86</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>85.9243117</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-87</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>86.9286886</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-88</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>87.9314175</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-89</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>88.9366691</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-90</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>89.9401</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-91</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>90.94596</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-92</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>91.94984</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-93</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>92.95629</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-94</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>93.96049</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Se-95</isotope>
    <atomic_number>34</atomic_number>
    <element_symbol>Se</element_symbol>
    <nist_symbol>Se</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>94.9673</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>78.971(8)</standard_atomic_weight>
    <notes>r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Br-67</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>67</mass_number>
    <neutrons>32</neutrons>
    <relative_atomic_mass>66.96465</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-68</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>68</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>67.95873</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-69</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>68.950497</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-70</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>69.944792</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-71</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>70.9393422</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-72</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>71.9365886</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-73</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>72.9316715</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-74</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>73.9299102</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000063</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-75</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>74.9258105</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-76</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>75.924542</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-77</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>76.9213792</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-78</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>77.9211459</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-79</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>78.9183376</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.5069</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-80</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>79.9185298</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-81</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>80.9162897</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.4931</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-82</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>81.9168032</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-83</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>82.9151756</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-84</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>83.916496</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-85</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>84.9156458</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-86</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>85.9188054</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-87</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>86.920674</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-88</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>87.9240833</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-89</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>88.9267046</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-90</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>89.9312928</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-91</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>90.9343986</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-92</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>91.9396316</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-93</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>92.94313</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-94</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>93.9489</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-95</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>94.95301</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-96</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>95.95903</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-97</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>96.96344</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Br-98</isotope>
    <atomic_number>35</atomic_number>
    <element_symbol>Br</element_symbol>
    <nist_symbol>Br</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>97.96946</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[79.901,79.907]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Kr-69</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>69</mass_number>
    <neutrons>33</neutrons>
    <relative_atomic_mass>68.96518</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-70</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>70</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>69.95604</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-71</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>70.95027</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-72</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>71.9420924</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-73</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>72.9392892</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000071</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-74</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>73.933084</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-75</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>74.9309457</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000087</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-76</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>75.9259103</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-77</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>76.92467</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-78</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>77.92036494</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00355</natural_abundance>
    <natural_abundance_uncertainty>0.00003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-79</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>78.9200829</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-80</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>79.91637808</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.02286</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-81</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>80.9165912</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-82</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>81.91348273</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.11593</natural_abundance>
    <natural_abundance_uncertainty>0.00031</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-83</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>82.91412716</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.115</natural_abundance>
    <natural_abundance_uncertainty>0.00019</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-84</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>83.9114977282</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.4e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.56987</natural_abundance>
    <natural_abundance_uncertainty>0.00015</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-85</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>84.9125273</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-86</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>85.9106106269</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.1e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.17279</natural_abundance>
    <natural_abundance_uncertainty>0.00041</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-87</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>86.91335476</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-88</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>87.9144479</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-89</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>88.9178355</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-90</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>89.9195279</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-91</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>90.9238063</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-92</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>91.9261731</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-93</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>92.9311472</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-94</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>93.93414</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-95</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>94.939711</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-96</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>95.943017</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-97</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>96.94909</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-98</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>97.95243</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-99</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>98.95839</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-100</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>99.96237</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Kr-101</isotope>
    <atomic_number>36</atomic_number>
    <element_symbol>Kr</element_symbol>
    <nist_symbol>Kr</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>100.96873</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>83.798(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Rb-71</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>71</mass_number>
    <neutrons>34</neutrons>
    <relative_atomic_mass>70.96532</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-72</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>72</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>71.95908</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-73</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>72.95053</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-74</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>73.9442659</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-75</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>74.9385732</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-76</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>75.935073</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-77</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>76.9304016</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-78</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>77.9281419</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-79</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>78.9239899</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-80</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>79.9225164</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-81</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>80.9189939</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-82</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>81.918209</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-83</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>82.9151142</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-84</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>83.9143752</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-85</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>84.9117897379</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.4e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.7217</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-86</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>85.91116743</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-87</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>86.909180531</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2783</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-88</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>87.91131559</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-89</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>88.9122783</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-90</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>89.9147985</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000007</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-91</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>90.9165372</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000084</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-92</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>91.9197284</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000066</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-93</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>92.9220393</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000084</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-94</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>93.9263948</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-95</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>94.92926</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-96</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>95.9341334</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-97</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>96.9371771</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-98</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>97.9416869</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-99</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>98.94503</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-100</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>99.95003</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-101</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>100.95404</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00023</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-102</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>101.95952</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rb-103</isotope>
    <atomic_number>37</atomic_number>
    <element_symbol>Rb</element_symbol>
    <nist_symbol>Rb</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>102.96392</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>85.4678(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sr-73</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>73</mass_number>
    <neutrons>35</neutrons>
    <relative_atomic_mass>72.9657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-74</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>74</mass_number>
    <neutrons>36</neutrons>
    <relative_atomic_mass>73.95617</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-75</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>75</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>74.94995</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-76</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>75.941763</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-77</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>76.9379455</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000085</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-78</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>77.93218</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-79</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>78.9297077</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000009</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-80</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>79.9245175</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-81</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>80.9232114</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-82</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>81.9183999</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-83</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>82.9175544</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-84</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>83.9134191</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0056</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-85</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>84.912932</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-86</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>85.9092606</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0986</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-87</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>86.9088775</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.07</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-88</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>87.9056125</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.8258</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-89</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>88.9074511</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-90</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>89.90773</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-91</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>90.9101954</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-92</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>91.9110382</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-93</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>92.9140242</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-94</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>93.9153556</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-95</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>94.9193529</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000063</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-96</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>95.9217066</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-97</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>96.926374</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-98</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>97.9286888</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-99</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>98.9328907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-100</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>99.93577</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-101</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>100.940352</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-102</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>101.943791</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-103</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>102.94909</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-104</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>103.95265</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-105</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>104.95855</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-106</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>105.96265</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Sr-107</isotope>
    <atomic_number>38</atomic_number>
    <element_symbol>Sr</element_symbol>
    <nist_symbol>Sr</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>106.96897</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>87.62(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Y-76</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>76</mass_number>
    <neutrons>37</neutrons>
    <relative_atomic_mass>75.95856</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-77</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>77</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>76.949781</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000065</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-78</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>77.94361</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-79</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>78.93735</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-80</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>79.9343561</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-81</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>80.9294556</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-82</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>81.9269314</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-83</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>82.922485</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-84</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>83.9206721</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-85</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>84.916433</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-86</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>85.914886</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-87</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>86.9108761</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-88</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>87.9095016</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-89</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>88.9058403</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-90</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>89.9071439</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-91</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>90.9072974</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-92</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>91.9089451</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000099</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-93</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>92.909578</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-94</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>93.9115906</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-95</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>94.9128161</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000074</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-96</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>95.9158968</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-97</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>96.9182741</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-98</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>97.9223821</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000088</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-99</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>98.924148</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000074</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-100</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>99.927715</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-101</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>100.9301477</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-102</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>101.9343277</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-103</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>102.937243</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-104</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>103.94196</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-105</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>104.94544</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-106</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>105.95056</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-107</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>106.95452</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-108</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>107.95996</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Y-109</isotope>
    <atomic_number>39</atomic_number>
    <element_symbol>Y</element_symbol>
    <nist_symbol>Y</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>108.96436</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>88.90584(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Zr-78</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>78</mass_number>
    <neutrons>38</neutrons>
    <relative_atomic_mass>77.95566</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-79</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>79</mass_number>
    <neutrons>39</neutrons>
    <relative_atomic_mass>78.94948</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-80</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>80</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>79.9404</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-81</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>80.93731</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-82</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>81.93135</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-83</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>82.9292421</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-84</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>83.9233269</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-85</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>84.9214444</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-86</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>85.9162972</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-87</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>86.914818</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-88</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>87.9102213</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-89</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>88.9088814</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-90</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>89.9046977</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.5145</natural_abundance>
    <natural_abundance_uncertainty>0.004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-91</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>90.9056396</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1122</natural_abundance>
    <natural_abundance_uncertainty>0.0005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-92</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>91.9050347</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1715</natural_abundance>
    <natural_abundance_uncertainty>0.0008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-93</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>92.9064699</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-94</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>93.9063108</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1738</natural_abundance>
    <natural_abundance_uncertainty>0.0028</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-95</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>94.9080385</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-96</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>95.9082714</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.028</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-97</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>96.9109512</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-98</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>97.9127289</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-99</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>98.916667</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-100</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>99.9180006</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-101</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>100.921448</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000091</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-102</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>101.9231409</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000097</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-103</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>102.927191</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-104</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>103.929436</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-105</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>104.934008</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-106</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>105.93676</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-107</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>106.94174</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-108</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>107.94487</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-109</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>108.95041</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-110</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>109.95396</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-111</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>110.95968</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Zr-112</isotope>
    <atomic_number>40</atomic_number>
    <element_symbol>Zr</element_symbol>
    <nist_symbol>Zr</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>111.9637</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>91.224(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nb-81</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>81</mass_number>
    <neutrons>40</neutrons>
    <relative_atomic_mass>80.9496</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-82</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>82</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>81.94396</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-83</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>82.93729</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-84</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>83.93449</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-85</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>84.9288458</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-86</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>85.9257828</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-87</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>86.9206937</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-88</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>87.918222</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-89</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>88.913445</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-90</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>89.9112584</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-91</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>90.9069897</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-92</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>91.9071881</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-93</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>92.906373</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-94</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>93.9072788</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-95</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>94.9068324</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-96</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>95.9080973</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-97</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>96.9080959</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-98</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>97.9103265</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-99</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>98.911613</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-100</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>99.9143276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000088</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-101</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>100.9153103</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-102</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>101.9180772</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-103</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>102.9194572</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-104</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>103.9228925</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-105</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>104.9249465</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-106</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>105.9289317</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-107</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>106.9315937</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000087</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-108</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>107.9360748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000088</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-109</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>108.93922</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-110</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>109.94403</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-111</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>110.94753</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-112</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>111.95247</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-113</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>112.95651</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-114</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>113.96201</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nb-115</isotope>
    <atomic_number>41</atomic_number>
    <element_symbol>Nb</element_symbol>
    <nist_symbol>Nb</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>114.96634</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>92.90637(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Mo-83</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>83</mass_number>
    <neutrons>41</neutrons>
    <relative_atomic_mass>82.94988</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-84</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>84</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>83.94149</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-85</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>84.938261</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-86</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>85.9311748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-87</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>86.9281962</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-88</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>87.9219678</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-89</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>88.9194682</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-90</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>89.9139309</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-91</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>90.9117453</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-92</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>91.90680796</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1453</natural_abundance>
    <natural_abundance_uncertainty>0.003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-93</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>92.90680958</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-94</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>93.9050849</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0915</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-95</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>94.90583877</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1584</natural_abundance>
    <natural_abundance_uncertainty>0.0011</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-96</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>95.90467612</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1667</natural_abundance>
    <natural_abundance_uncertainty>0.0015</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-97</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>96.90601812</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.096</natural_abundance>
    <natural_abundance_uncertainty>0.0014</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-98</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>97.90540482</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2439</natural_abundance>
    <natural_abundance_uncertainty>0.0037</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-99</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>98.90770851</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-100</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>99.9074718</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0982</natural_abundance>
    <natural_abundance_uncertainty>0.0031</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-101</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>100.9103414</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-102</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>101.9102834</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000091</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-103</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>102.913079</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-104</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>103.9137344</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-105</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>104.916969</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-106</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>105.918259</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-107</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>106.922106</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-108</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>107.924033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-109</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>108.928424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-110</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>109.930704</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-111</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>110.935654</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-112</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>111.93831</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-113</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>112.94335</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-114</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>113.94653</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-115</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>114.95196</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-116</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>115.95545</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Mo-117</isotope>
    <atomic_number>42</atomic_number>
    <element_symbol>Mo</element_symbol>
    <nist_symbol>Mo</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>116.96117</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>95.95(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Tc-85</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>85</mass_number>
    <neutrons>42</neutrons>
    <relative_atomic_mass>84.95058</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-86</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>86</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>85.94493</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-87</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>86.9380672</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-88</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>87.93378</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-89</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>88.9276487</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-90</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>89.9240739</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-91</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>90.9184254</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-92</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>91.9152698</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-93</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>92.910246</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-94</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>93.9096536</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-95</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>94.9076536</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-96</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>95.907868</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-97</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>96.9063667</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-98</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>97.9072124</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-99</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>98.9062508</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-100</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>99.9076539</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-101</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>100.907309</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-102</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>101.9092097</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000099</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-103</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>102.909176</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-104</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>103.911425</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-105</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>104.911655</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-106</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>105.914358</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-107</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>106.9154606</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-108</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>107.9184957</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000094</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-109</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>108.920256</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-110</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>109.923744</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-111</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>110.925901</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-112</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>111.9299458</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000006</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-113</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>112.932569</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-114</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>113.93691</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-115</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>114.93998</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-116</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>115.94476</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-117</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>116.94806</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-118</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>117.95299</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-119</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>118.95666</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tc-120</isotope>
    <atomic_number>43</atomic_number>
    <element_symbol>Tc</element_symbol>
    <nist_symbol>Tc</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>119.96187</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[98]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ru-87</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>87</mass_number>
    <neutrons>43</neutrons>
    <relative_atomic_mass>86.95069</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-88</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>88</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>87.9416</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-89</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>88.93762</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-90</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>89.9303444</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-91</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>90.9267419</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-92</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>91.9202344</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-93</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>92.9171044</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-94</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>93.9113429</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-95</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>94.910406</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-96</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>95.90759025</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0554</natural_abundance>
    <natural_abundance_uncertainty>0.0014</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-97</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>96.9075471</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-98</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>97.9052868</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0187</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-99</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>98.9059341</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1276</natural_abundance>
    <natural_abundance_uncertainty>0.0014</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-100</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>99.9042143</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.126</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-101</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>100.9055769</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1706</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-102</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>101.9043441</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.3155</natural_abundance>
    <natural_abundance_uncertainty>0.0014</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-103</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>102.9063186</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-104</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>103.9054275</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1862</natural_abundance>
    <natural_abundance_uncertainty>0.0027</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-105</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>104.9077476</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-106</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>105.9073291</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-107</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>106.909972</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-108</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>107.910188</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-109</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>108.913326</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000096</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-110</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>109.9140407</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000096</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-111</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>110.91757</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-112</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>111.918809</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-113</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>112.922844</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-114</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>113.9246136</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-115</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>114.92882</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000071</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-116</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>115.9312192</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-117</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>116.9361</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00063</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-118</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>117.93853</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-119</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>118.94357</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-120</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>119.94631</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-121</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>120.95164</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-122</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>121.95447</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-123</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>122.95989</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ru-124</isotope>
    <atomic_number>44</atomic_number>
    <element_symbol>Ru</element_symbol>
    <nist_symbol>Ru</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>123.96305</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>101.07(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Rh-89</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>89</mass_number>
    <neutrons>44</neutrons>
    <relative_atomic_mass>88.95058</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-90</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>90</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>89.94422</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-91</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>90.93688</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-92</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>91.9323677</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-93</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>92.9259128</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-94</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>93.9217305</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-95</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>94.9158979</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-96</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>95.914453</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-97</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>96.911329</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-98</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>97.910708</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-99</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>98.9081282</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-100</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>99.908117</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-101</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>100.9061606</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000063</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-102</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>101.9068374</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-103</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>102.905498</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-104</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>103.9066492</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-105</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>104.9056885</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-106</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>105.9072868</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-107</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>106.906748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-108</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>107.908714</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-109</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>108.9087488</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-110</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>109.911079</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-111</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>110.9116423</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000074</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-112</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>111.914403</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-113</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>112.9154393</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-114</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>113.918718</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-115</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>114.9203116</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-116</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>115.924059</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-117</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>116.9260354</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000095</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-118</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>117.93034</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-119</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>118.932557</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-120</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>119.93686</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-121</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>120.93942</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-122</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>121.94399</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-123</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>122.94685</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-124</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>123.95151</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-125</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>124.95469</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rh-126</isotope>
    <atomic_number>45</atomic_number>
    <element_symbol>Rh</element_symbol>
    <nist_symbol>Rh</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>125.95946</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>102.90550(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pd-91</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>91</mass_number>
    <neutrons>45</neutrons>
    <relative_atomic_mass>90.95032</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-92</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>92</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>91.94088</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-93</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>92.93651</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-94</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>93.9290376</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-95</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>94.9248898</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-96</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>95.9182151</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-97</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>96.916472</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000052</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-98</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>97.9126983</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-99</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>98.9117748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-100</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>99.908505</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-101</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>100.9082864</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-102</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>101.9056022</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0102</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-103</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>102.9060809</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-104</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>103.9040305</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1114</natural_abundance>
    <natural_abundance_uncertainty>0.0008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-105</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>104.9050796</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2233</natural_abundance>
    <natural_abundance_uncertainty>0.0008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-106</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>105.9034804</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2733</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-107</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>106.9051282</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-108</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>107.9038916</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2646</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-109</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>108.9059504</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-110</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>109.9051722</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1172</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-111</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>110.90768968</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-112</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>111.9073297</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000007</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-113</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>112.910261</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-114</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>113.9103686</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-115</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>114.913659</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-116</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>115.914297</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-117</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>116.9179547</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-118</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>117.9190667</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-119</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>118.9233402</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-120</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>119.9245511</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-121</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>120.9289503</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-122</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>121.930632</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-123</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>122.93514</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-124</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>123.93714</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-125</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>124.94179</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-126</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>125.94416</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-127</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>126.94907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pd-128</isotope>
    <atomic_number>46</atomic_number>
    <element_symbol>Pd</element_symbol>
    <nist_symbol>Pd</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>127.95183</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>106.42(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-93</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>93</mass_number>
    <neutrons>46</neutrons>
    <relative_atomic_mass>92.95033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-94</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>94</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>93.94373</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00069</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-95</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>94.93602</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-96</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>95.930744</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000097</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-97</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>96.92397</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-98</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>97.92156</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-99</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>98.9176458</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-100</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>99.9161154</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-101</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>100.912684</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000052</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-102</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>101.9117047</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000088</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-103</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>102.9089631</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-104</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>103.9086239</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-105</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>104.9065256</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-106</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>105.9066636</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-107</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>106.9050916</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.51839</natural_abundance>
    <natural_abundance_uncertainty>0.00008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-108</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>107.9059503</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-109</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>108.9047553</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.48161</natural_abundance>
    <natural_abundance_uncertainty>0.00008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-110</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>109.9061102</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-111</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>110.9052959</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-112</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>111.9070486</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-113</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>112.906573</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-114</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>113.908823</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-115</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>114.908767</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-116</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>115.9113868</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-117</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>116.911774</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-118</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>117.9145955</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-119</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>118.91557</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-120</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>119.9187848</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-121</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>120.920125</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-122</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>121.923664</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-123</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>122.925337</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-124</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>123.92893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-125</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>124.93105</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-126</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>125.93475</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-127</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>126.93711</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-128</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>127.94106</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-129</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>128.94395</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ag-130</isotope>
    <atomic_number>47</atomic_number>
    <element_symbol>Ag</element_symbol>
    <nist_symbol>Ag</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>129.9507</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00036</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>107.8682(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-95</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>95</mass_number>
    <neutrons>47</neutrons>
    <relative_atomic_mass>94.94994</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-96</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>96</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>95.94034</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-97</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>96.9351</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-98</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>97.927389</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-99</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>98.9249258</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-100</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>99.9203488</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-101</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>100.9185862</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-102</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>101.914482</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-103</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>102.9134165</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-104</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>103.9098564</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-105</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>104.9094639</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-106</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>105.9064599</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0125</natural_abundance>
    <natural_abundance_uncertainty>0.0006</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-107</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>106.9066121</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-108</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>107.9041834</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0089</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-109</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>108.9049867</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-110</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>109.90300661</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1249</natural_abundance>
    <natural_abundance_uncertainty>0.0018</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-111</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>110.90418287</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.128</natural_abundance>
    <natural_abundance_uncertainty>0.0012</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-112</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>111.90276287</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2413</natural_abundance>
    <natural_abundance_uncertainty>0.0021</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-113</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>112.90440813</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1222</natural_abundance>
    <natural_abundance_uncertainty>0.0012</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-114</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>113.90336509</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2873</natural_abundance>
    <natural_abundance_uncertainty>0.0042</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-115</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>114.90543751</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-116</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>115.90476315</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0749</natural_abundance>
    <natural_abundance_uncertainty>0.0018</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-117</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>116.907226</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-118</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>117.906922</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-119</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>118.909847</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-120</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>119.9098681</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-121</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>120.9129637</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-122</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>121.9134591</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-123</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>122.9168925</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-124</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>123.9176574</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-125</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>124.9212576</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-126</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>125.9224291</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-127</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>126.926472</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-128</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>127.9278129</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-129</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>128.93182</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-130</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>129.93394</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-131</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>130.9406</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-132</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>131.94604</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Cd-133</isotope>
    <atomic_number>48</atomic_number>
    <element_symbol>Cd</element_symbol>
    <nist_symbol>Cd</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>132.95285</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>112.414(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>In-97</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>97</mass_number>
    <neutrons>48</neutrons>
    <relative_atomic_mass>96.94934</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-98</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>98</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>97.94214</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-99</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>98.93411</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-100</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>99.93096</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-101</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>100.92634</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-102</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>101.9241071</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-103</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>102.9198819</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-104</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>103.9182145</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-105</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>104.914502</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-106</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>105.913464</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-107</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>106.91029</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-108</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>107.9096935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-109</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>108.9071514</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-110</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>109.90717</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-111</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>110.9051085</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-112</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>111.9055377</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-113</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>112.90406184</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0429</natural_abundance>
    <natural_abundance_uncertainty>0.0005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-114</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>113.90491791</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-115</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>114.903878776</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.2e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.9571</natural_abundance>
    <natural_abundance_uncertainty>0.0005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-116</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>115.90525999</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-117</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>116.9045157</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000052</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-118</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>117.9063566</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000083</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-119</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>118.9058507</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-120</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>119.907967</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-121</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>120.907851</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-122</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>121.910281</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-123</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>122.910434</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-124</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>123.913182</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-125</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>124.913605</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-126</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>125.916507</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-127</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>126.917446</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-128</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>127.9204</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-129</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>128.9218053</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-130</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>129.924977</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-131</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>130.9269715</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-132</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>131.933001</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-133</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>132.93831</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-134</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>133.94454</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>In-135</isotope>
    <atomic_number>49</atomic_number>
    <element_symbol>In</element_symbol>
    <nist_symbol>In</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>134.95005</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>114.818(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sn-99</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>99</mass_number>
    <neutrons>49</neutrons>
    <relative_atomic_mass>98.94853</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-100</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>100</mass_number>
    <neutrons>50</neutrons>
    <relative_atomic_mass>99.9385</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-101</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>101</mass_number>
    <neutrons>51</neutrons>
    <relative_atomic_mass>100.93526</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-102</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>102</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>101.93029</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-103</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>102.928105</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-104</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>103.9231052</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-105</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>104.9212684</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-106</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>105.9169574</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-107</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>106.9157137</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-108</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>107.9118943</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-109</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>108.9112921</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000085</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-110</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>109.907845</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-111</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>110.9077401</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-112</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>111.90482387</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0097</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-113</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>112.9051757</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-114</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>113.9027827</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0066</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-115</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>114.903344699</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.6e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0034</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-116</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>115.9017428</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1454</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-117</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>116.90295398</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0768</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-118</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>117.90160657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2422</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-119</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>118.90331117</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.8e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0859</natural_abundance>
    <natural_abundance_uncertainty>0.0004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-120</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>119.90220163</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.3258</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-121</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>120.9042426</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-122</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>121.9034438</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0463</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-123</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>122.9057252</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-124</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>123.9052766</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0579</natural_abundance>
    <natural_abundance_uncertainty>0.0005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-125</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>124.9077864</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-126</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>125.907659</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-127</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>126.91039</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-128</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>127.910507</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-129</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>128.913465</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-130</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>129.9139738</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-131</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>130.917045</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000065</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-132</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>131.9178267</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-133</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>132.9239134</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-134</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>133.9286821</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-135</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>134.9349086</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-136</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>135.93999</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-137</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>136.94655</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sn-138</isotope>
    <atomic_number>50</atomic_number>
    <element_symbol>Sn</element_symbol>
    <nist_symbol>Sn</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>137.95184</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>118.710(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-103</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>103</mass_number>
    <neutrons>52</neutrons>
    <relative_atomic_mass>102.93969</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-104</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>104</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>103.93648</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-105</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>104.931276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-106</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>105.928638</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-107</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>106.9241506</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-108</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>107.9222267</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-109</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>108.9181411</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-110</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>109.9168543</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-111</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>110.9132182</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000095</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-112</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>111.9124</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-113</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>112.909375</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-114</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>113.90929</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-115</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>114.906598</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-116</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>115.9067931</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-117</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>116.9048415</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000091</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-118</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>117.9055321</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-119</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>118.9039455</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000083</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-120</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>119.9050794</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-121</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>120.903812</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.5721</natural_abundance>
    <natural_abundance_uncertainty>0.0005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-122</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>121.9051699</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-123</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>122.9042132</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.4279</natural_abundance>
    <natural_abundance_uncertainty>0.0005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-124</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>123.905935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-125</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>124.905253</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-126</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>125.907253</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-127</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>126.9069243</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-128</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>127.909146</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-129</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>128.909147</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-130</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>129.911662</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-131</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>130.9119888</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-132</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>131.9145077</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-133</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>132.9152732</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-134</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>133.9205357</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-135</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>134.9251851</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-136</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>135.9307459</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000068</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-137</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>136.93555</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-138</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>137.94145</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-139</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>138.94655</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sb-140</isotope>
    <atomic_number>51</atomic_number>
    <element_symbol>Sb</element_symbol>
    <nist_symbol>Sb</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>139.95283</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>121.760(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-105</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>105</mass_number>
    <neutrons>53</neutrons>
    <relative_atomic_mass>104.9433</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-106</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>106</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>105.9375</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-107</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>106.935012</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-108</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>107.9293805</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-109</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>108.9273045</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-110</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>109.9224581</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000071</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-111</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>110.9210006</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-112</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>111.9167279</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000009</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-113</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>112.915891</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-114</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>113.912089</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-115</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>114.911902</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-116</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>115.90846</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-117</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>116.908646</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-118</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>117.905854</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-119</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>118.9064071</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000085</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-120</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>119.9040593</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0009</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-121</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>120.904944</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-122</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>121.9030435</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0255</natural_abundance>
    <natural_abundance_uncertainty>0.0012</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-123</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>122.9042698</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0089</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-124</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>123.9028171</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0474</natural_abundance>
    <natural_abundance_uncertainty>0.0014</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-125</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>124.9044299</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0707</natural_abundance>
    <natural_abundance_uncertainty>0.0015</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-126</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>125.9033109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1884</natural_abundance>
    <natural_abundance_uncertainty>0.0025</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-127</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>126.9052257</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-128</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>127.90446128</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.3174</natural_abundance>
    <natural_abundance_uncertainty>0.0008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-129</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>128.90659646</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-130</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>129.906222748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.2e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.3408</natural_abundance>
    <natural_abundance_uncertainty>0.0062</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-131</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>130.908522213</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.5e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-132</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>131.9085467</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-133</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>132.9109688</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-134</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>133.911394</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-135</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>134.9165557</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-136</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>135.9201006</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-137</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>136.9255989</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-138</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>137.9294722</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-139</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>138.9353672</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-140</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>139.939499</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-141</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>140.9458</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-142</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>141.95022</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Te-143</isotope>
    <atomic_number>52</atomic_number>
    <element_symbol>Te</element_symbol>
    <nist_symbol>Te</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>142.95676</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>127.60(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>I-107</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>107</mass_number>
    <neutrons>54</neutrons>
    <relative_atomic_mass>106.94678</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-108</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>108</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>107.94348</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-109</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>108.9380853</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-110</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>109.935089</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-111</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>110.9302692</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-112</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>111.928005</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-113</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>112.9236501</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-114</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>113.92185</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-115</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>114.918048</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-116</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>115.91681</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-117</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>116.913648</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-118</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>117.913074</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-119</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>118.910074</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-120</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>119.910087</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-121</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>120.9074051</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-122</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>121.9075888</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-123</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>122.9055885</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-124</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>123.906209</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-125</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>124.9046294</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-126</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>125.9056233</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-127</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>126.9044719</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-128</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>127.9058086</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-129</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>128.9049837</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-130</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>129.9066702</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-131</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>130.9061263</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-132</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>131.9079935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-133</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>132.907797</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-134</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>133.9097588</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-135</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>134.9100488</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-136</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>135.914604</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-137</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>136.9180282</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000009</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-138</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>137.9227264</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-139</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>138.926506</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-140</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>139.93173</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-141</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>140.93569</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-142</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>141.9412</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-143</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>142.94565</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-144</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>143.95139</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>I-145</isotope>
    <atomic_number>53</atomic_number>
    <element_symbol>I</element_symbol>
    <nist_symbol>I</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>144.95605</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>126.90447(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Xe-109</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>109</mass_number>
    <neutrons>55</neutrons>
    <relative_atomic_mass>108.95043</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-110</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>110</mass_number>
    <neutrons>56</neutrons>
    <relative_atomic_mass>109.94426</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-111</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>111</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>110.941607</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-112</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>111.935559</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-113</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>112.9332217</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-114</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>113.92798</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-115</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>114.926294</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-116</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>115.921581</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-117</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>116.920359</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-118</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>117.916179</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-119</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>118.915411</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-120</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>119.911784</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-121</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>120.911453</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-122</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>121.908368</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-123</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>122.908482</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-124</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>123.905892</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.000952</natural_abundance>
    <natural_abundance_uncertainty>0.000003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-125</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>124.9063944</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-126</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>125.9042983</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00089</natural_abundance>
    <natural_abundance_uncertainty>0.000002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-127</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>126.9051829</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-128</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>127.903531</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.019102</natural_abundance>
    <natural_abundance_uncertainty>0.000008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-129</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>128.9047808611</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.264006</natural_abundance>
    <natural_abundance_uncertainty>0.000082</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-130</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>129.903509349</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.04071</natural_abundance>
    <natural_abundance_uncertainty>0.000013</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-131</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>130.90508406</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.212324</natural_abundance>
    <natural_abundance_uncertainty>0.00003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-132</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>131.9041550856</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.6e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.269086</natural_abundance>
    <natural_abundance_uncertainty>0.000033</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-133</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>132.9059108</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-134</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>133.90539466</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.104357</natural_abundance>
    <natural_abundance_uncertainty>0.000021</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-135</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>134.9072278</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-136</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>135.907214484</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.1e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.088573</natural_abundance>
    <natural_abundance_uncertainty>0.000044</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-137</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>136.91155778</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-138</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>137.9141463</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-139</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>138.9187922</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-140</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>139.9216458</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-141</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>140.9267872</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-142</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>141.9299731</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-143</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>142.9353696</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-144</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>143.9389451</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-145</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>144.94472</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-146</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>145.948518</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-147</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>146.95426</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Xe-148</isotope>
    <atomic_number>54</atomic_number>
    <element_symbol>Xe</element_symbol>
    <nist_symbol>Xe</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>147.95813</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>131.293(6)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Cs-112</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>112</mass_number>
    <neutrons>57</neutrons>
    <relative_atomic_mass>111.950309</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-113</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>113</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>112.9444291</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-114</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>113.941296</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-115</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>114.93591</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-116</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>115.93337</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-117</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>116.928617</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-118</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>117.92656</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-119</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>118.922377</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-120</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>119.920677</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-121</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>120.917227</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-122</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>121.916108</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-123</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>122.912996</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-124</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>123.9122578</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-125</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>124.909728</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000083</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-126</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>125.909446</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-127</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>126.9074174</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000006</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-128</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>127.9077487</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-129</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>128.9060657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-130</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>129.9067093</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000009</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-131</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>130.9054649</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-132</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>131.9064339</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-133</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>132.905451961</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>8e-9</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-134</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>133.906718503</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>1.7e-8</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-135</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>134.905977</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-136</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>135.9073114</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-137</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>136.90708923</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-138</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>137.9110171</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-139</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>138.9133638</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-140</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>139.9172831</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000088</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-141</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>140.9200455</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-142</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>141.924296</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-143</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>142.927349</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-144</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>143.932076</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-145</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>144.935527</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-146</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>145.940344</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-147</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>146.944156</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-148</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>147.94923</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-149</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>148.95302</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-150</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>149.95833</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Cs-151</isotope>
    <atomic_number>55</atomic_number>
    <element_symbol>Cs</element_symbol>
    <nist_symbol>Cs</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>150.96258</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>132.90545196(6)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-114</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>114</mass_number>
    <neutrons>58</neutrons>
    <relative_atomic_mass>113.95066</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-115</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>115</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>114.94737</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-116</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>115.94128</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-117</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>116.93814</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-118</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>117.93306</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-119</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>118.93066</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-120</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>119.92605</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-121</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>120.92405</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-122</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>121.919904</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-123</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>122.918781</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-124</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>123.915094</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-125</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>124.914472</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-126</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>125.91125</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-127</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>126.911091</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-128</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>127.908342</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-129</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>128.908681</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-130</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>129.9063207</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00106</natural_abundance>
    <natural_abundance_uncertainty>0.00001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-131</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>130.906941</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-132</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>131.9050611</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00101</natural_abundance>
    <natural_abundance_uncertainty>0.00001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-133</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>132.9060074</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-134</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>133.90450818</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.02417</natural_abundance>
    <natural_abundance_uncertainty>0.00018</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-135</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>134.90568838</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.06592</natural_abundance>
    <natural_abundance_uncertainty>0.00012</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-136</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>135.90457573</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>2.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.07854</natural_abundance>
    <natural_abundance_uncertainty>0.00024</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-137</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>136.90582714</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.11232</natural_abundance>
    <natural_abundance_uncertainty>0.00024</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-138</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>137.905247</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.71698</natural_abundance>
    <natural_abundance_uncertainty>0.00042</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-139</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>138.9088411</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>3.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-140</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>139.9106057</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000085</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-141</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>140.9144033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-142</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>141.9164324</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-143</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>142.9206253</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000074</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-144</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>143.9229549</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-145</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>144.9275184</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000091</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-146</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>145.930284</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-147</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>146.935304</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-148</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>147.938171</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000068</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-149</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>148.94308</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-150</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>149.94605</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-151</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>150.95127</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-152</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>151.95481</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ba-153</isotope>
    <atomic_number>56</atomic_number>
    <element_symbol>Ba</element_symbol>
    <nist_symbol>Ba</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>152.96036</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>137.327(7)</standard_atomic_weight>
  </row>
  <row>
    <isotope>La-116</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>116</mass_number>
    <neutrons>59</neutrons>
    <relative_atomic_mass>115.9563</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00023</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-117</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>117</mass_number>
    <neutrons>60</neutrons>
    <relative_atomic_mass>116.94999</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-118</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>118</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>117.94673</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-119</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>118.94099</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-120</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>119.93807</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-121</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>120.93315</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-122</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>121.93071</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-123</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>122.9263</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-124</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>123.924574</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-125</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>124.920816</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-126</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>125.919513</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000097</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-127</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>126.916375</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-128</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>127.915592</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-129</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>128.912694</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-130</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>129.912369</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-131</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>130.91007</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-132</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>131.910119</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-133</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>132.908218</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-134</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>133.908514</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-135</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>134.906984</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-136</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>135.907635</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-137</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>136.9064504</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-138</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>137.9071149</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0008881</natural_abundance>
    <natural_abundance_uncertainty>0.0000071</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-139</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>138.9063563</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.9991119</natural_abundance>
    <natural_abundance_uncertainty>0.0000071</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-140</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>139.9094806</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-141</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>140.910966</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-142</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>141.9140909</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-143</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>142.9160795</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-144</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>143.919646</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-145</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>144.921808</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-146</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>145.925875</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-147</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>146.928418</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-148</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>147.932679</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-149</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>148.93535</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-150</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>149.93947</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-151</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>150.94232</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-152</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>151.94682</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-153</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>152.95036</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-154</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>153.95517</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>La-155</isotope>
    <atomic_number>57</atomic_number>
    <element_symbol>La</element_symbol>
    <nist_symbol>La</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>154.95901</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>138.90547(7)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-119</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>119</mass_number>
    <neutrons>61</neutrons>
    <relative_atomic_mass>118.95271</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-120</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>120</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>119.94654</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-121</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>120.94335</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-122</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>121.93787</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-123</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>122.93528</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-124</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>123.93031</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-125</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>124.92844</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-126</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>125.923971</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-127</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>126.922727</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-128</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>127.918911</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-129</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>128.918102</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-130</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>129.914736</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-131</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>130.914429</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-132</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>131.911464</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-133</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>132.91152</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-134</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>133.908928</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-135</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>134.909161</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-136</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>135.90712921</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00185</natural_abundance>
    <natural_abundance_uncertainty>0.00002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-137</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>136.90776236</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.5e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-138</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>137.905991</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00251</natural_abundance>
    <natural_abundance_uncertainty>0.00002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-139</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>138.9066551</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-140</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>139.9054431</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.8845</natural_abundance>
    <natural_abundance_uncertainty>0.00051</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-141</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>140.9082807</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-142</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>141.9092504</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.11114</natural_abundance>
    <natural_abundance_uncertainty>0.00051</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-143</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>142.9123921</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-144</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>143.9136529</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-145</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>144.917265</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-146</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>145.918802</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-147</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>146.9226899</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000092</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-148</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>147.924424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-149</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>148.928427</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-150</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>149.930384</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-151</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>150.934272</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-152</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>151.9366</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-153</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>152.94093</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-154</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>153.9438</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-155</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>154.94855</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-156</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>155.95183</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ce-157</isotope>
    <atomic_number>58</atomic_number>
    <element_symbol>Ce</element_symbol>
    <nist_symbol>Ce</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>156.95705</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.116(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pr-121</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>121</mass_number>
    <neutrons>62</neutrons>
    <relative_atomic_mass>120.95532</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-122</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>122</mass_number>
    <neutrons>63</neutrons>
    <relative_atomic_mass>121.95175</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-123</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>123</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>122.94596</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-124</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>123.94294</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-125</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>124.9377</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-126</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>125.93524</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-127</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>126.93071</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-128</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>127.928791</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-129</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>128.925095</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-130</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>129.92359</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-131</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>130.920235</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-132</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>131.919255</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-133</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>132.916331</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-134</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>133.915697</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-135</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>134.913112</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-136</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>135.912677</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-137</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>136.9106792</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000087</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-138</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>137.910754</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-139</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>138.9089408</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000085</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-140</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>139.9090803</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-141</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>140.9076576</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-142</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>141.9100496</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-143</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>142.9108228</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-144</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>143.9133109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-145</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>144.9145182</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-146</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>145.91768</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-147</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>146.919008</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-148</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>147.92213</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-149</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>148.923736</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-150</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>149.9266765</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000097</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-151</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>150.928309</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-152</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>151.931553</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-153</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>152.933904</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-154</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>153.93753</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-155</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>154.940509</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-156</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>155.94464</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-157</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>156.94789</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-158</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>157.95241</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pr-159</isotope>
    <atomic_number>59</atomic_number>
    <element_symbol>Pr</element_symbol>
    <nist_symbol>Pr</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>158.95589</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>140.90766(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Nd-124</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>124</mass_number>
    <neutrons>64</neutrons>
    <relative_atomic_mass>123.9522</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-125</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>125</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>124.9489</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-126</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>125.94311</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-127</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>126.94038</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-128</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>127.93525</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-129</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>128.9331</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-130</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>129.928506</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-131</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>130.927248</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-132</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>131.923321</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-133</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>132.922348</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-134</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>133.91879</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-135</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>134.918181</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-136</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>135.914976</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-137</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>136.914562</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-138</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>137.91195</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-139</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>138.911954</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-140</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>139.90955</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-141</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>140.9096147</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-142</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>141.907729</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.27152</natural_abundance>
    <natural_abundance_uncertainty>0.0004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-143</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>142.90982</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.12174</natural_abundance>
    <natural_abundance_uncertainty>0.00026</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-144</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>143.910093</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.23798</natural_abundance>
    <natural_abundance_uncertainty>0.00019</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-145</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>144.9125793</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.08293</natural_abundance>
    <natural_abundance_uncertainty>0.00012</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-146</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>145.9131226</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.17189</natural_abundance>
    <natural_abundance_uncertainty>0.00032</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-147</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>146.9161061</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-148</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>147.9168993</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.05756</natural_abundance>
    <natural_abundance_uncertainty>0.00021</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-149</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>148.9201548</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-150</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>149.9209022</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.05638</natural_abundance>
    <natural_abundance_uncertainty>0.00028</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-151</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>150.9238403</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-152</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>151.924692</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-153</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>152.927718</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-154</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>153.92948</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-155</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>154.9331357</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-156</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>155.93508</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-157</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>156.939386</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-158</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>157.94197</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-159</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>158.94653</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-160</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>159.9494</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Nd-161</isotope>
    <atomic_number>60</atomic_number>
    <element_symbol>Nd</element_symbol>
    <nist_symbol>Nd</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>160.95428</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>144.242(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pm-126</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>126</mass_number>
    <neutrons>65</neutrons>
    <relative_atomic_mass>125.95792</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-127</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>127</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>126.95192</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-128</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>127.9487</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-129</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>128.94323</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-130</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>129.94053</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-131</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>130.93567</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-132</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>131.93384</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-133</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>132.929782</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-134</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>133.928353</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-135</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>134.924823</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00007</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-136</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>135.923585</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-137</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>136.92048</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-138</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>137.919548</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-139</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>138.9168</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-140</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>139.91604</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-141</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>140.913555</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-142</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>141.91289</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-143</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>142.9109383</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-144</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>143.9125964</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-145</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>144.9127559</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-146</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>145.9147024</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-147</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>146.915145</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-148</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>147.9174819</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000063</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-149</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>148.9183423</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-150</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>149.920991</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-151</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>150.9212175</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-152</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>151.923506</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-153</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>152.9241567</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000097</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-154</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>153.926472</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-155</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>154.928137</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-156</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>155.9311175</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-157</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>156.9331214</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-158</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>157.936565</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-159</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>158.939287</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-160</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>159.9431</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-161</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>160.94607</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-162</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>161.95022</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pm-163</isotope>
    <atomic_number>61</atomic_number>
    <element_symbol>Pm</element_symbol>
    <nist_symbol>Pm</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>162.95357</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[145]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Sm-128</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>128</mass_number>
    <neutrons>66</neutrons>
    <relative_atomic_mass>127.95842</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-129</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>129</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>128.95476</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-130</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>129.949</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-131</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>130.94618</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-132</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>131.94087</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-133</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>132.93856</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-134</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>133.93411</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-135</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>134.93252</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-136</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>135.928276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-137</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>136.926971</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-138</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>137.923244</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-139</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>138.922297</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-140</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>139.918995</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-141</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>140.9184816</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000092</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-142</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>141.9152044</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-143</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>142.9146353</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-144</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>143.9120065</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0307</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-145</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>144.9134173</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-146</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>145.913047</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-147</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>146.9149044</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1499</natural_abundance>
    <natural_abundance_uncertainty>0.0018</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-148</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>147.9148292</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1124</natural_abundance>
    <natural_abundance_uncertainty>0.001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-149</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>148.9171921</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1382</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-150</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>149.9172829</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0738</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-151</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>150.9199398</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-152</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>151.9197397</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2675</natural_abundance>
    <natural_abundance_uncertainty>0.0016</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-153</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>152.9221047</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-154</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>153.9222169</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2275</natural_abundance>
    <natural_abundance_uncertainty>0.0029</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-155</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>154.9246477</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-156</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>155.925536</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-157</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>156.9284187</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-158</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>157.929951</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-159</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>158.9332172</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-160</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>159.9353353</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-161</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>160.9391602</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-162</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>161.94146</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-163</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>162.94555</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-164</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>163.94836</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Sm-165</isotope>
    <atomic_number>62</atomic_number>
    <element_symbol>Sm</element_symbol>
    <nist_symbol>Sm</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>164.95297</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>150.36(2)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-130</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>130</mass_number>
    <neutrons>67</neutrons>
    <relative_atomic_mass>129.96369</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-131</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>131</mass_number>
    <neutrons>68</neutrons>
    <relative_atomic_mass>130.95784</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-132</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>132</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>131.95467</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-133</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>132.94929</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-134</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>133.9464</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-135</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>134.94187</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-136</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>135.93962</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-137</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>136.93546</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-138</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>137.933709</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-139</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>138.929792</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-140</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>139.928088</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-141</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>140.924932</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-142</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>141.923442</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-143</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>142.920299</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-144</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>143.91882</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-145</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>144.9162726</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-146</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>145.917211</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000065</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-147</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>146.9167527</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-148</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>147.918089</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-149</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>148.9179378</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-150</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>149.9197077</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000068</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-151</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>150.9198578</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.4781</natural_abundance>
    <natural_abundance_uncertainty>0.0006</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-152</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>151.9217522</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-153</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>152.921238</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.5219</natural_abundance>
    <natural_abundance_uncertainty>0.0006</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-154</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>153.922987</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-155</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>154.9229011</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-156</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>155.9247605</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-157</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>156.9254334</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-158</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>157.927799</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-159</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>158.9291001</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-160</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>159.931851</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-161</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>160.933664</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-162</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>161.936989</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000065</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-163</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>162.939196</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-164</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>163.94274</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-165</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>164.94559</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00035</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-166</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>165.94962</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Eu-167</isotope>
    <atomic_number>63</atomic_number>
    <element_symbol>Eu</element_symbol>
    <nist_symbol>Eu</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>166.95289</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>151.964(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-133</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>133</mass_number>
    <neutrons>69</neutrons>
    <relative_atomic_mass>132.96133</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-134</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>134</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>133.95566</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-135</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>134.95245</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-136</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>135.9473</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-137</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>136.94502</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-138</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>137.94025</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-139</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>138.93813</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-140</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>139.933674</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-141</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>140.932126</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-142</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>141.928116</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-143</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>142.92675</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-144</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>143.922963</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-145</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>144.921713</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-146</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>145.9183188</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-147</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>146.9191014</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-148</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>147.9181215</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-149</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>148.9193481</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-150</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>149.9186644</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000066</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-151</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>150.920356</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-152</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>151.9197995</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.002</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-153</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>152.921758</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-154</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>153.9208741</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0218</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-155</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>154.9226305</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.148</natural_abundance>
    <natural_abundance_uncertainty>0.0012</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-156</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>155.9221312</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2047</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-157</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>156.9239686</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1565</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-158</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>157.9241123</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2484</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-159</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>158.926397</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-160</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>159.9270624</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2186</natural_abundance>
    <natural_abundance_uncertainty>0.0019</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-161</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>160.9296775</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-162</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>161.930993</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-163</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>162.9341769</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000009</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-164</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>163.93583</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-165</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>164.93936</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-166</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>165.94146</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-167</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>166.94545</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-168</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>167.94808</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Gd-169</isotope>
    <atomic_number>64</atomic_number>
    <element_symbol>Gd</element_symbol>
    <nist_symbol>Gd</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>168.9526</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>157.25(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Tb-135</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>135</mass_number>
    <neutrons>70</neutrons>
    <relative_atomic_mass>134.96476</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-136</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>136</mass_number>
    <neutrons>71</neutrons>
    <relative_atomic_mass>135.96129</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-137</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>137</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>136.95602</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-138</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>137.95312</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-139</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>138.94833</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-140</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>139.94581</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-141</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>140.94145</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-142</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>141.93928</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-143</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>142.935137</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-144</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>143.933045</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-145</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>144.92882</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-146</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>145.927253</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-147</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>146.9240548</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000087</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-148</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>147.924282</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-149</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>148.9232535</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-150</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>149.9236649</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-151</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>150.9231096</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-152</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>151.924083</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-153</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>152.9234424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-154</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>153.924685</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-155</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>154.923511</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-156</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>155.9247552</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-157</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>156.924033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-158</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>157.9254209</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-159</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>158.9253547</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-160</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>159.9271756</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-161</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>160.9275778</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-162</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>161.929495</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-163</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>162.9306547</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-164</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>163.93336</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-165</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>164.93498</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-166</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>165.93786</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-167</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>166.93996</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-168</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>167.9434</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-169</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>168.94597</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-170</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>169.94984</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tb-171</isotope>
    <atomic_number>65</atomic_number>
    <element_symbol>Tb</element_symbol>
    <nist_symbol>Tb</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>170.95273</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>158.92535(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Dy-138</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>138</mass_number>
    <neutrons>72</neutrons>
    <relative_atomic_mass>137.9625</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-139</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>139</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>138.95959</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-140</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>139.95402</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-141</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>140.95128</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-142</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>141.94619</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00078</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-143</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>142.943994</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-144</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>143.9392695</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-145</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>144.937474</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000007</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-146</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>145.9328445</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-147</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>146.9310827</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000095</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-148</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>147.927157</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-149</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>148.927322</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-150</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>149.9255933</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-151</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>150.9261916</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-152</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>151.9247253</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-153</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>152.9257724</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-154</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>153.9244293</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-155</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>154.925759</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-156</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>155.9242847</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00056</natural_abundance>
    <natural_abundance_uncertainty>0.00003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-157</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>156.9254707</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-158</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>157.9244159</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00095</natural_abundance>
    <natural_abundance_uncertainty>0.00003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-159</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>158.925747</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-160</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>159.9252046</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.02329</natural_abundance>
    <natural_abundance_uncertainty>0.00018</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-161</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>160.9269405</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.18889</natural_abundance>
    <natural_abundance_uncertainty>0.00042</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-162</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>161.9268056</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.25475</natural_abundance>
    <natural_abundance_uncertainty>0.00036</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-163</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>162.9287383</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.24896</natural_abundance>
    <natural_abundance_uncertainty>0.00042</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-164</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>163.9291819</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2826</natural_abundance>
    <natural_abundance_uncertainty>0.00054</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-165</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>164.9317105</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-166</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>165.9328139</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-167</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>166.935661</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000065</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-168</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>167.93713</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-169</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>168.94031</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-170</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>169.94239</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-171</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>170.94612</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-172</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>171.94846</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Dy-173</isotope>
    <atomic_number>66</atomic_number>
    <element_symbol>Dy</element_symbol>
    <nist_symbol>Dy</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>172.95283</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>162.500(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ho-140</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>140</mass_number>
    <neutrons>73</neutrons>
    <relative_atomic_mass>139.96859</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-141</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>141</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>140.96311</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-142</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>141.96001</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-143</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>142.95486</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-144</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>143.9521097</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000091</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-145</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>144.9472674</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-146</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>145.9449935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000071</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-147</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>146.9401423</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-148</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>147.937744</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00009</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-149</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>148.933803</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-150</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>149.933498</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-151</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>150.9316983</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-152</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>151.931724</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-153</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>152.9302064</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-154</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>153.9306068</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-155</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>154.929104</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-156</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>155.929706</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-157</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>156.928254</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-158</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>157.928946</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-159</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>158.9277197</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-160</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>159.928737</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-161</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>160.9278615</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-162</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>161.9291023</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-163</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>162.928741</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-164</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>163.9302403</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-165</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>164.9303288</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-166</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>165.9322909</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-167</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>166.9331385</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-168</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>167.935522</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-169</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>168.936878</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-170</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>169.939625</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-171</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>170.94147</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-172</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>171.94473</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-173</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>172.94702</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-174</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>173.95095</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ho-175</isotope>
    <atomic_number>67</atomic_number>
    <element_symbol>Ho</element_symbol>
    <nist_symbol>Ho</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>174.95362</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>164.93033(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Er-142</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>142</mass_number>
    <neutrons>74</neutrons>
    <relative_atomic_mass>141.9701</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-143</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>143</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>142.96662</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-144</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>143.9607</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-145</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>144.95805</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-146</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>145.9524184</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-147</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>146.949964</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-148</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>147.944735</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-149</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>148.942306</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-150</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>149.937916</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-151</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>150.937449</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-152</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>151.935057</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-153</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>152.93508</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-154</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>153.9327908</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-155</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>154.9332159</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-156</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>155.931067</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-157</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>156.931949</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-158</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>157.929893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-159</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>158.9306918</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-160</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>159.929077</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-161</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>160.9300046</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000096</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-162</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>161.9287884</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00139</natural_abundance>
    <natural_abundance_uncertainty>0.00005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-163</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>162.9300408</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-164</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>163.9292088</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.01601</natural_abundance>
    <natural_abundance_uncertainty>0.00003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-165</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>164.9307345</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-166</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>165.9302995</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.33503</natural_abundance>
    <natural_abundance_uncertainty>0.00036</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-167</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>166.9320546</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.22869</natural_abundance>
    <natural_abundance_uncertainty>0.00009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-168</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>167.9323767</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.26978</natural_abundance>
    <natural_abundance_uncertainty>0.00018</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-169</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>168.9345968</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-170</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>169.9354702</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1491</natural_abundance>
    <natural_abundance_uncertainty>0.00036</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-171</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>170.9380357</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-172</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>171.9393619</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-173</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>172.9424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-174</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>173.94423</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-175</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>174.94777</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-176</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>175.94994</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Er-177</isotope>
    <atomic_number>68</atomic_number>
    <element_symbol>Er</element_symbol>
    <nist_symbol>Er</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>176.95399</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>167.259(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Tm-144</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>144</mass_number>
    <neutrons>75</neutrons>
    <relative_atomic_mass>143.97628</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-145</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>145</mass_number>
    <neutrons>76</neutrons>
    <relative_atomic_mass>144.97039</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-146</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>146</mass_number>
    <neutrons>77</neutrons>
    <relative_atomic_mass>145.96684</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-147</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>147</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>146.9613799</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-148</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>147.958384</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-149</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>148.95289</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-150</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>149.95009</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-151</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>150.945488</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-152</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>151.944422</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-153</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>152.94204</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-154</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>153.94157</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-155</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>154.93921</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-156</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>155.938992</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-157</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>156.936944</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-158</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>157.93698</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-159</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>158.934975</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-160</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>159.935263</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-161</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>160.933549</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-162</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>161.934002</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-163</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>162.9326592</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-164</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>163.933544</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-165</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>164.9324431</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-166</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>165.933561</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-167</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>166.9328562</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-168</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>167.9341774</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-169</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>168.9342179</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-170</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>169.935806</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-171</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>170.9364339</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-172</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>171.9384055</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-173</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>172.9396084</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-174</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>173.942173</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-175</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>174.943841</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-176</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>175.947</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-177</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>176.94904</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-178</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>177.95264</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tm-179</isotope>
    <atomic_number>69</atomic_number>
    <element_symbol>Tm</element_symbol>
    <nist_symbol>Tm</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>178.95534</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>168.93422(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Yb-148</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>148</mass_number>
    <neutrons>78</neutrons>
    <relative_atomic_mass>147.96758</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-149</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>149</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>148.96436</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-150</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>149.95852</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-151</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>150.9554</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-152</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>151.95027</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-153</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>152.94932</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-154</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>153.946396</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-155</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>154.945783</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-156</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>155.942825</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-157</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>156.942645</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-158</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>157.9398705</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-159</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>158.940055</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-160</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>159.937557</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-161</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>160.937907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-162</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>161.935774</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-163</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>162.93634</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-164</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>163.934495</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-165</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>164.93527</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-166</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>165.9338747</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-167</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>166.934953</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-168</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>167.9338896</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00123</natural_abundance>
    <natural_abundance_uncertainty>0.00003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-169</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>168.9351825</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-170</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>169.9347664</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.02982</natural_abundance>
    <natural_abundance_uncertainty>0.00039</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-171</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>170.9363302</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1409</natural_abundance>
    <natural_abundance_uncertainty>0.0014</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-172</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>171.9363859</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2168</natural_abundance>
    <natural_abundance_uncertainty>0.0013</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-173</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>172.9382151</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.16103</natural_abundance>
    <natural_abundance_uncertainty>0.00063</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-174</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>173.9388664</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.32026</natural_abundance>
    <natural_abundance_uncertainty>0.0008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-175</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>174.9412808</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-176</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>175.9425764</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.12996</natural_abundance>
    <natural_abundance_uncertainty>0.00083</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-177</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>176.9452656</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-178</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>177.946651</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-179</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>178.95004</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-180</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>179.95212</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Yb-181</isotope>
    <atomic_number>70</atomic_number>
    <element_symbol>Yb</element_symbol>
    <nist_symbol>Yb</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>180.95589</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>173.054(5)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-150</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>150</mass_number>
    <neutrons>79</neutrons>
    <relative_atomic_mass>149.97355</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-151</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>151</mass_number>
    <neutrons>80</neutrons>
    <relative_atomic_mass>150.96768</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-152</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>152</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>151.96412</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-153</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>152.95875</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-154</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>153.95736</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-155</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>154.954321</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-156</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>155.953033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-157</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>156.950127</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-158</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>157.949316</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-159</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>158.946636</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-160</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>159.946033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-161</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>160.943572</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-162</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>161.943283</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-163</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>162.941179</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-164</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>163.941339</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-165</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>164.939407</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-166</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>165.939859</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-167</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>166.93827</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-168</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>167.938736</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-169</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>168.9376441</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-170</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>169.938478</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-171</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>170.937917</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-172</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>171.9390891</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-173</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>172.938934</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-174</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>173.9403409</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-175</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>174.9407752</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.97401</natural_abundance>
    <natural_abundance_uncertainty>0.00013</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-176</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>175.9426897</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.02599</natural_abundance>
    <natural_abundance_uncertainty>0.00013</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-177</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>176.9437615</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-178</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>177.945958</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-179</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>178.9473309</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-180</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>179.949888</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-181</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>180.95191</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-182</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>181.95504</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-183</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>182.957363</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-184</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>183.96091</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Lu-185</isotope>
    <atomic_number>71</atomic_number>
    <element_symbol>Lu</element_symbol>
    <nist_symbol>Lu</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>184.96362</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>174.9668(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Hf-153</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>153</mass_number>
    <neutrons>81</neutrons>
    <relative_atomic_mass>152.97069</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-154</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>154</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>153.96486</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-155</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>154.96311</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-156</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>155.95935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-157</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>156.95824</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-158</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>157.954801</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-159</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>158.953996</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-160</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>159.950691</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-161</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>160.950278</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-162</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>161.9472148</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000097</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-163</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>162.947113</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-164</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>163.944371</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-165</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>164.944567</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-166</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>165.94218</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-167</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>166.9426</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-168</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>167.940568</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-169</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>168.941259</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-170</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>169.939609</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-171</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>170.940492</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-172</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>171.93945</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-173</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>172.940513</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-174</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>173.9400461</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0016</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-175</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>174.9415092</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-176</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>175.9414076</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0526</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-177</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>176.9432277</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.186</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-178</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>177.9437058</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2728</natural_abundance>
    <natural_abundance_uncertainty>0.0007</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-179</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>178.9458232</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1362</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-180</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>179.946557</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.3508</natural_abundance>
    <natural_abundance_uncertainty>0.0016</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-181</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>180.9491083</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-182</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>181.9505612</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000068</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-183</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>182.95353</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-184</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>183.955446</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
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  <row>
    <isotope>Hf-185</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>184.958862</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
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  <row>
    <isotope>Hf-186</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>185.960897</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
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  <row>
    <isotope>Hf-187</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>186.96477</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-188</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>187.96685</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hf-189</isotope>
    <atomic_number>72</atomic_number>
    <element_symbol>Hf</element_symbol>
    <nist_symbol>Hf</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>188.97084</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>178.49(2)</standard_atomic_weight>
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  <row>
    <isotope>Ta-155</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>155</mass_number>
    <neutrons>82</neutrons>
    <relative_atomic_mass>154.97424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
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  <row>
    <isotope>Ta-156</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>156</mass_number>
    <neutrons>83</neutrons>
    <relative_atomic_mass>155.97203</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-157</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>157</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>156.96818</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-158</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>158</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>157.96654</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-159</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>158.963023</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-160</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>159.961488</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-161</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>160.958452</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-162</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>161.957294</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-163</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>162.954337</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-164</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>163.953534</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-165</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>164.950781</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-166</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>165.950512</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-167</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>166.948093</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-168</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>167.948047</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-169</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>168.946011</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
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  <row>
    <isotope>Ta-170</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>169.946175</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-171</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>170.944476</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
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  <row>
    <isotope>Ta-172</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>171.944895</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-173</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>172.94375</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
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  <row>
    <isotope>Ta-174</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>173.944454</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
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  <row>
    <isotope>Ta-175</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>174.943737</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
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  <row>
    <isotope>Ta-176</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>175.944857</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-177</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>176.9444795</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
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  <row>
    <isotope>Ta-178</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>177.945678</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000056</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-179</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>178.9459366</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-180</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>179.9474648</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0001201</natural_abundance>
    <natural_abundance_uncertainty>0.0000032</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-181</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>180.9479958</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.9998799</natural_abundance>
    <natural_abundance_uncertainty>0.0000032</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-182</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>181.9501519</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-183</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>182.9513726</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-184</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>183.954008</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-185</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>184.955559</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-186</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>185.958551</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-187</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>186.960386</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000071</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>180.94788(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ta-188</isotope>
    <atomic_number>73</atomic_number>
    <element_symbol>Ta</element_symbol>
    <nist_symbol>Ta</nist_symbol>
    <mass_number>188</mass_number>
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    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>183.84(1)</standard_atomic_weight>
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    <isotope>W-192</isotope>
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    <nist_symbol>W</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>191.96817</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>183.84(1)</standard_atomic_weight>
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  <row>
    <isotope>W-193</isotope>
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    <element_symbol>W</element_symbol>
    <nist_symbol>W</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>192.97178</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>183.84(1)</standard_atomic_weight>
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  <row>
    <isotope>W-194</isotope>
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    <element_symbol>W</element_symbol>
    <nist_symbol>W</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>193.97367</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>183.84(1)</standard_atomic_weight>
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    <isotope>Re-159</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>159</mass_number>
    <neutrons>84</neutrons>
    <relative_atomic_mass>158.98418</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-160</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>160</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>159.98182</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-161</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>160.97757</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-162</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>161.97584</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-163</isotope>
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    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>162.97208</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-164</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>163.970453</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-165</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>164.967103</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-166</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>165.965761</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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  <row>
    <isotope>Re-167</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>166.962595</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000044</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-168</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>167.961573</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-169</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>168.958766</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-170</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>169.95822</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-171</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>170.955716</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-172</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>171.95542</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-173</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>172.953243</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-174</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>173.953115</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-175</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>174.951381</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-176</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>176</mass_number>
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    <relative_atomic_mass>175.951623</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-177</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>176.950328</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-178</isotope>
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    <mass_number>178</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>177.950989</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-179</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>104</neutrons>
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    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-180</isotope>
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    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>179.950792</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-181</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>180.950058</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-182</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>181.95121</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-183</isotope>
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    <element_symbol>Re</element_symbol>
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    <mass_number>183</mass_number>
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    <relative_atomic_mass>182.9508196</relative_atomic_mass>
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    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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    <isotope>Re-184</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
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    <mass_number>184</mass_number>
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    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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    <isotope>Re-185</isotope>
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    <mass_number>185</mass_number>
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    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.374</natural_abundance>
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    <naturally_occurring>true</naturally_occurring>
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    <isotope>Re-186</isotope>
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    <mass_number>186</mass_number>
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    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.626</natural_abundance>
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    <naturally_occurring>true</naturally_occurring>
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    <isotope>Re-188</isotope>
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    <mass_number>188</mass_number>
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    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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    <isotope>Re-189</isotope>
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    <mass_number>189</mass_number>
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    <relative_atomic_mass>188.959226</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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    <isotope>Re-190</isotope>
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    <element_symbol>Re</element_symbol>
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    <mass_number>190</mass_number>
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    <relative_atomic_mass>189.961744</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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    <isotope>Re-191</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>190.963122</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
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    <isotope>Re-192</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>192</mass_number>
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    <relative_atomic_mass>191.966088</relative_atomic_mass>
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    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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    <isotope>Re-193</isotope>
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    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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    <mass_estimated>true</mass_estimated>
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    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>194.97254</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Re-196</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>195.9758</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Re-197</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>196.97799</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Re-198</isotope>
    <atomic_number>75</atomic_number>
    <element_symbol>Re</element_symbol>
    <nist_symbol>Re</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>197.9816</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>186.207(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Os-161</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>161</mass_number>
    <neutrons>85</neutrons>
    <relative_atomic_mass>160.98903</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-162</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>162</mass_number>
    <neutrons>86</neutrons>
    <relative_atomic_mass>161.98443</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-163</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>163</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>162.98241</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-164</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>163.97802</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-165</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>164.9766</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-166</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>165.972692</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-167</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>166.971549</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-168</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>167.967808</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-169</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>168.967018</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-170</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>169.963578</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-171</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>170.963174</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-172</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>171.960017</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-173</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>172.959808</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-174</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>173.957064</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-175</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>174.956945</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-176</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>175.954806</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-177</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>176.954966</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-178</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>177.953254</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-179</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>178.953817</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-180</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>179.952375</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-181</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>180.953247</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-182</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>181.95211</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-183</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>182.953125</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-184</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>183.9524885</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0002</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-185</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>184.9540417</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-186</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>185.953835</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0159</natural_abundance>
    <natural_abundance_uncertainty>0.0003</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-187</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>186.9557474</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0196</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-188</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>187.9558352</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1324</natural_abundance>
    <natural_abundance_uncertainty>0.0008</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-189</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>188.9581442</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1615</natural_abundance>
    <natural_abundance_uncertainty>0.0005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-190</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>189.9584437</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2626</natural_abundance>
    <natural_abundance_uncertainty>0.0002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-191</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>190.9609264</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-192</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>191.961477</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.4078</natural_abundance>
    <natural_abundance_uncertainty>0.0019</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-193</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>192.9641479</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-194</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>193.9651772</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-195</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>194.968318</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000065</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-196</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>195.969641</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-197</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>196.97283</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-198</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>197.97441</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-199</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>198.97801</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-200</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>199.97984</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-201</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>200.98364</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Os-202</isotope>
    <atomic_number>76</atomic_number>
    <element_symbol>Os</element_symbol>
    <nist_symbol>Os</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>201.98595</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>190.23(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Ir-164</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>164</mass_number>
    <neutrons>87</neutrons>
    <relative_atomic_mass>163.99191</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00034</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-165</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>165</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>164.9875</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-166</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>165.98566</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-167</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>166.981666</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-168</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>167.979907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-169</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>168.976298</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-170</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>169.974922</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000095</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-171</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>170.97164</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-172</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>171.970607</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-173</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>172.967506</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-174</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>173.966861</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-175</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>174.96415</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-176</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>175.96365</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-177</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>176.961301</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-178</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>177.961082</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-179</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>178.95912</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-180</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>179.959229</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-181</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>180.957625</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-182</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>181.958076</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-183</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>182.95684</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-184</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>183.957476</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-185</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>184.956698</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-186</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>185.957944</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-187</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>186.957542</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-188</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>187.958828</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-189</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>188.958715</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-190</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>189.9605412</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-191</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>190.9605893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.373</natural_abundance>
    <natural_abundance_uncertainty>0.002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-192</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>191.9626002</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-193</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>192.9629216</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.627</natural_abundance>
    <natural_abundance_uncertainty>0.002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-194</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>193.9650735</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-195</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>194.9659747</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-196</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>195.968397</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-197</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>196.969655</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-198</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>197.97228</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-199</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>198.973805</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000044</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-200</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>199.9768</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-201</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>200.97864</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-202</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>201.98199</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-203</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>202.98423</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ir-204</isotope>
    <atomic_number>77</atomic_number>
    <element_symbol>Ir</element_symbol>
    <nist_symbol>Ir</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>203.9896</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>192.217(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-166</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>166</mass_number>
    <neutrons>88</neutrons>
    <relative_atomic_mass>165.99486</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-167</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>167</mass_number>
    <neutrons>89</neutrons>
    <relative_atomic_mass>166.99269</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-168</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>168</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>167.98813</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-169</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>168.98657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-170</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>169.982496</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-171</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>170.981245</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-172</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>171.977351</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-173</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>172.976443</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00006</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-174</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>173.97282</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-175</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>174.97241</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-176</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>175.968938</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-177</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>176.96847</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-178</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>177.96565</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-179</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>178.965359</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-180</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>179.963032</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-181</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>180.963098</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-182</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>181.961172</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-183</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>182.961597</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-184</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>183.959915</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-185</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>184.960614</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-186</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>185.959351</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-187</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>186.960617</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-188</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>187.9593889</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-189</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>188.960831</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-190</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>189.9599297</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000063</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00012</natural_abundance>
    <natural_abundance_uncertainty>0.00002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-191</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>190.9616729</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-192</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>191.9610387</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.00782</natural_abundance>
    <natural_abundance_uncertainty>0.00024</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-193</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>192.9629824</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-194</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>193.9626809</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.3286</natural_abundance>
    <natural_abundance_uncertainty>0.004</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-195</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>194.9647917</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.3378</natural_abundance>
    <natural_abundance_uncertainty>0.0024</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-196</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>195.96495209</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2521</natural_abundance>
    <natural_abundance_uncertainty>0.0034</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-197</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>196.96734069</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>9.4e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-198</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>197.9678949</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.07356</natural_abundance>
    <natural_abundance_uncertainty>0.0013</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-199</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>198.9705952</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-200</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>199.971443</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-201</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>200.974513</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-202</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>201.975639</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-203</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>202.97893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-204</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>203.98076</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-205</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>204.98608</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pt-206</isotope>
    <atomic_number>78</atomic_number>
    <element_symbol>Pt</element_symbol>
    <nist_symbol>Pt</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>205.98966</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>195.084(9)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-169</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>169</mass_number>
    <neutrons>90</neutrons>
    <relative_atomic_mass>168.99808</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-170</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>170</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>169.99597</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-171</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>170.991876</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-172</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>171.989942</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-173</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>172.986241</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-174</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>173.984717</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000095</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-175</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>174.981304</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-176</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>175.98025</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-177</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>176.97687</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-178</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>177.976032</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-179</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>178.973174</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-180</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>179.972523</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-181</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>180.970079</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-182</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>181.969618</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-183</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>182.967591</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-184</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>183.967452</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-185</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>184.96579</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-186</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>185.965953</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-187</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>186.964543</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-188</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>187.965349</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-189</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>188.963948</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-190</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>189.964698</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-191</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>190.963702</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-192</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>191.964814</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-193</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>192.9641373</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-194</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>193.9654178</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-195</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>194.9650352</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-196</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>195.9665699</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-197</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>196.96656879</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7.1e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-198</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>197.96824242</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-199</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>198.96876528</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-200</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>199.970756</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-201</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>200.9716575</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-202</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>201.973856</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-203</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>202.9751544</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-204</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>203.97783</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-205</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>204.97985</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-206</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>205.98474</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-207</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>206.9884</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-208</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>207.99345</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-209</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>208.99735</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Au-210</isotope>
    <atomic_number>79</atomic_number>
    <element_symbol>Au</element_symbol>
    <nist_symbol>Au</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>210.0025</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>196.966569(5)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-171</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>171</mass_number>
    <neutrons>91</neutrons>
    <relative_atomic_mass>171.00353</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-172</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>172</mass_number>
    <neutrons>92</neutrons>
    <relative_atomic_mass>171.99881</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-173</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>173</mass_number>
    <neutrons>93</neutrons>
    <relative_atomic_mass>172.99709</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-174</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>174</mass_number>
    <neutrons>94</neutrons>
    <relative_atomic_mass>173.992865</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-175</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>175</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>174.991441</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-176</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>175.987361</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-177</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>176.986277</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-178</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>177.982484</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-179</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>178.981831</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-180</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>179.97826</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-181</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>180.977819</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-182</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>181.974689</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-183</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>182.9744448</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-184</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>183.971714</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-185</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>184.971899</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-186</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>185.969362</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-187</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>186.969814</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-188</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>187.967567</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-189</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>188.968195</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-190</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>189.966323</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-191</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>190.967157</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-192</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>191.965635</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-193</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>192.966653</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-194</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>193.9654491</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-195</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>194.966721</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-196</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>195.9658326</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0015</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-197</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>196.9672128</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-198</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>197.9667686</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.2e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0997</natural_abundance>
    <natural_abundance_uncertainty>0.002</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-199</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>198.96828064</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.6e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1687</natural_abundance>
    <natural_abundance_uncertainty>0.0022</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-200</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>199.96832659</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>4.7e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.231</natural_abundance>
    <natural_abundance_uncertainty>0.0019</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-201</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>200.97030284</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.1318</natural_abundance>
    <natural_abundance_uncertainty>0.0009</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-202</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>201.9706434</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>6.9e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2986</natural_abundance>
    <natural_abundance_uncertainty>0.0026</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-203</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>202.9728728</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-204</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>203.97349398</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>5.3e-7</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.0687</natural_abundance>
    <natural_abundance_uncertainty>0.0015</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-205</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>204.9760734</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-206</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>205.977514</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-207</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>206.9823</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-208</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>207.985759</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-209</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>208.99072</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-210</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>209.99424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-211</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>210.99933</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-212</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>212.00296</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-213</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>213.00823</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-214</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>214.012</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-215</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>215.0174</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Hg-216</isotope>
    <atomic_number>80</atomic_number>
    <element_symbol>Hg</element_symbol>
    <nist_symbol>Hg</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>216.02132</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>200.592(3)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-176</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>176</mass_number>
    <neutrons>95</neutrons>
    <relative_atomic_mass>176.000624</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-177</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>177</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>176.996431</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-178</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>177.99485</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-179</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>178.991111</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-180</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>179.990057</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-181</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>180.98626</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-182</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>181.985713</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000063</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-183</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>182.982193</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-184</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>183.981886</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-185</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>184.978789</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-186</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>185.978651</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-187</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>186.9759063</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000088</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-188</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>187.976021</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-189</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>188.973588</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-190</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>189.973828</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-191</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>190.9717842</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000079</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-192</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>191.972225</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-193</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>192.970502</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-194</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>193.971081</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-195</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>194.969774</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-196</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>195.970481</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-197</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>196.969576</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-198</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>197.970483</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-199</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>198.969877</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-200</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>199.9709633</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-201</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>200.970822</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-202</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>201.972102</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-203</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>202.9723446</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.2952</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-204</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>203.9738639</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-205</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>204.9744278</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.7048</natural_abundance>
    <natural_abundance_uncertainty>0.0001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-206</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>205.9761106</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-207</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>206.9774197</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-208</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>207.982019</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-209</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>208.9853594</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-210</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>209.990074</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-211</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>210.993475</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-212</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>211.99834</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-213</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>213.001915</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-214</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>214.00694</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-215</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>215.01064</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-216</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>216.0158</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-217</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>217.01966</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Tl-218</isotope>
    <atomic_number>81</atomic_number>
    <element_symbol>Tl</element_symbol>
    <nist_symbol>Tl</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>218.02479</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[204.382,204.385]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pb-178</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>178</mass_number>
    <neutrons>96</neutrons>
    <relative_atomic_mass>178.003831</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-179</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>179</mass_number>
    <neutrons>97</neutrons>
    <relative_atomic_mass>179.002201</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-180</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>180</mass_number>
    <neutrons>98</neutrons>
    <relative_atomic_mass>179.997928</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-181</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>181</mass_number>
    <neutrons>99</neutrons>
    <relative_atomic_mass>180.996653</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000081</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-182</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>182</mass_number>
    <neutrons>100</neutrons>
    <relative_atomic_mass>181.992672</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-183</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>183</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>182.991872</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-184</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>183.988136</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-185</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>184.98761</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-186</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>185.984238</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-187</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>186.9839109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-188</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>187.980875</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-189</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>188.980807</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-190</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>189.978082</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-191</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>190.978276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-192</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>191.975775</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-193</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>192.976173</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-194</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>193.974012</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-195</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>194.974543</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-196</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>195.972774</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-197</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>196.9734312</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000006</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-198</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>197.972034</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-199</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>198.972913</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-200</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>199.971819</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-201</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>200.972883</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-202</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>201.972152</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000004</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-203</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>202.9733911</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000071</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-204</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>203.973044</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.014</natural_abundance>
    <natural_abundance_uncertainty>0.001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-205</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>204.9744822</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-206</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>205.9744657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.241</natural_abundance>
    <natural_abundance_uncertainty>0.001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-207</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>206.9758973</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.221</natural_abundance>
    <natural_abundance_uncertainty>0.001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-208</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>207.9766525</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.524</natural_abundance>
    <natural_abundance_uncertainty>0.001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-209</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>208.9810905</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-210</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>209.9841889</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-211</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>210.9887371</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-212</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>211.9918977</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-213</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>212.9965629</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-214</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>213.9998059</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-215</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>215.00474</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-216</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>216.00803</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-217</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>217.01314</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-218</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>218.01659</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-219</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>219.02177</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Pb-220</isotope>
    <atomic_number>82</atomic_number>
    <element_symbol>Pb</element_symbol>
    <nist_symbol>Pb</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>220.02541</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>207.2(1)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; r: range in isotopic composition limits precision</notes>
  </row>
  <row>
    <isotope>Bi-184</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>184</mass_number>
    <neutrons>101</neutrons>
    <relative_atomic_mass>184.001275</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000084</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-185</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>185</mass_number>
    <neutrons>102</neutrons>
    <relative_atomic_mass>184.9976</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000087</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-186</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>186</mass_number>
    <neutrons>103</neutrons>
    <relative_atomic_mass>185.996644</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000065</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Bi-187</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>187</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>186.993147</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-188</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>187.992287</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-189</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>188.989195</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-190</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>189.988622</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-191</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>190.9857866</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-192</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>191.985469</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-193</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>192.98296</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-194</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>193.982785</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-195</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>194.9806488</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-196</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>195.980667</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-197</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>196.9788651</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-198</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>197.979206</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-199</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>198.977673</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-200</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>199.978131</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-201</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>200.97701</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-202</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>201.977734</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-203</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>202.976893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-204</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>203.9778361</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000099</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-205</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>204.9773867</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-206</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>205.9784993</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000082</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-207</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>206.978471</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-208</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>207.9797425</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-209</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>208.9803991</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-210</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>209.9841207</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-211</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>210.9872697</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-212</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>211.991286</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-213</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>212.9943851</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-214</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>213.998712</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-215</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>215.00177</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-216</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>216.006306</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-217</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>217.009372</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-218</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>218.014188</relative_atomic_mass>
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    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-219</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>219.01748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Bi-220</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>220</mass_number>
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    <relative_atomic_mass>220.02235</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-221</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>221.02587</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-222</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>222</mass_number>
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    <relative_atomic_mass>222.03078</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-223</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>223.0345</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Bi-224</isotope>
    <atomic_number>83</atomic_number>
    <element_symbol>Bi</element_symbol>
    <nist_symbol>Bi</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>224.03947</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>208.98040(1)</standard_atomic_weight>
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  <row>
    <isotope>Po-186</isotope>
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    <nist_symbol>Po</nist_symbol>
    <mass_number>186</mass_number>
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    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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  </row>
  <row>
    <isotope>Po-187</isotope>
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    <nist_symbol>Po</nist_symbol>
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    <neutrons>103</neutrons>
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    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-188</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>188</mass_number>
    <neutrons>104</neutrons>
    <relative_atomic_mass>187.999416</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-189</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>189</mass_number>
    <neutrons>105</neutrons>
    <relative_atomic_mass>188.998473</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-190</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>190</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>189.995101</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-191</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>190.9945585</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-192</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>191.991336</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-193</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>192.991026</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-194</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>193.988186</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-195</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>194.988126</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-196</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>195.985526</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-197</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>196.98566</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-198</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>197.983389</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-199</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>198.983667</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-200</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>199.981799</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-201</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>200.9822598</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000063</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-202</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>201.980758</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-203</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>202.9814161</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-204</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>203.98031</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-205</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>204.981203</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-206</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>205.980474</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-207</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>206.9815938</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000072</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-208</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>207.9812461</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-209</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>208.9824308</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-210</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>209.9828741</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-211</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>210.9866536</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-212</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>211.9888684</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-213</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>212.9928576</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-214</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>213.9952017</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-215</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>214.9994201</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-216</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>216.0019152</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-217</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>217.0063182</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-218</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>218.0089735</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-219</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>219.013614</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-220</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>220.016386</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-221</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>221.021228</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-222</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>222.02414</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000043</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-223</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>223.02907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-224</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>224.03211</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-225</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>225</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>225.03707</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-226</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>226</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>226.04031</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Po-227</isotope>
    <atomic_number>84</atomic_number>
    <element_symbol>Po</element_symbol>
    <nist_symbol>Po</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>227.04539</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[209]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-191</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>191</mass_number>
    <neutrons>106</neutrons>
    <relative_atomic_mass>191.004148</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-192</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>192</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>192.003152</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-193</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>192.999927</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-194</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>193.999236</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-195</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>194.9962685</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-196</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>195.9958</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-197</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>196.993189</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-198</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>197.992784</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-199</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>198.9905277</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-200</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>199.990351</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-201</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>200.9884171</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000088</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-202</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>201.98863</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-203</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>202.986943</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-204</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>203.987251</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-205</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>204.986076</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-206</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>205.986657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-207</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>206.9858</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-208</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>207.9866133</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000096</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-209</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>208.9861702</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-210</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>209.9871479</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000083</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-211</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>210.9874966</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-212</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>211.9907377</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-213</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>212.992937</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-214</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>213.9963721</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000046</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-215</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>214.9986528</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-216</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>216.0024236</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000039</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
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  <row>
    <isotope>At-217</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>217.0047192</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
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  <row>
    <isotope>At-218</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>218.008695</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-219</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>219.0111618</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-220</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>220.015433</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-221</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>221.018017</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-222</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>222.022494</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-223</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>223.025151</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-224</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>224.029749</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-225</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>225</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>225.03263</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-226</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>226</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>226.03716</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-227</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>227.04024</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-228</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>228</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>228.04475</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>At-229</isotope>
    <atomic_number>85</atomic_number>
    <element_symbol>At</element_symbol>
    <nist_symbol>At</nist_symbol>
    <mass_number>229</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>229.04812</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[210]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-193</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>193</mass_number>
    <neutrons>107</neutrons>
    <relative_atomic_mass>193.009708</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-194</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>194</mass_number>
    <neutrons>108</neutrons>
    <relative_atomic_mass>194.006144</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-195</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>195</mass_number>
    <neutrons>109</neutrons>
    <relative_atomic_mass>195.005422</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-196</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>196</mass_number>
    <neutrons>110</neutrons>
    <relative_atomic_mass>196.002116</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-197</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>197</mass_number>
    <neutrons>111</neutrons>
    <relative_atomic_mass>197.001585</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-198</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>198</mass_number>
    <neutrons>112</neutrons>
    <relative_atomic_mass>197.998679</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-199</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>199</mass_number>
    <neutrons>113</neutrons>
    <relative_atomic_mass>198.99839</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000068</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-200</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>200</mass_number>
    <neutrons>114</neutrons>
    <relative_atomic_mass>199.99569</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-201</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>201</mass_number>
    <neutrons>115</neutrons>
    <relative_atomic_mass>200.995628</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-202</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>202</mass_number>
    <neutrons>116</neutrons>
    <relative_atomic_mass>201.993264</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-203</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>203</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>202.993388</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-204</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>204</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>203.99143</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-205</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>205</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>204.991719</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-206</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>205.990214</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-207</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>206.9907303</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000091</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-208</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>207.989635</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-209</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>208.990415</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-210</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>209.9896891</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-211</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>210.9906011</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-212</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>211.9907039</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-213</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>212.9938831</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-214</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>213.995363</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000099</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-215</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>214.9987459</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000083</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Rn-216</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>216.0002719</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000065</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[222]</standard_atomic_weight>
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  <row>
    <isotope>Rn-217</isotope>
    <atomic_number>86</atomic_number>
    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>217.003928</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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  </row>
  <row>
    <isotope>Rn-218</isotope>
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    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>218.0056016</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  </row>
  <row>
    <isotope>Rn-219</isotope>
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    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>219.0094804</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-220</isotope>
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    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>220.0113941</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-221</isotope>
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    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>221.0155371</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000063</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  </row>
  <row>
    <isotope>Rn-222</isotope>
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    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>222.0175782</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-223</isotope>
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    <element_symbol>Rn</element_symbol>
    <nist_symbol>Rn</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>223.0218893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000084</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-224</isotope>
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    <mass_number>224</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>224.024096</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-225</isotope>
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    <element_symbol>Rn</element_symbol>
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    <mass_number>225</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>225.028486</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-226</isotope>
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    <mass_number>226</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>226.030861</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
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  <row>
    <isotope>Rn-227</isotope>
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    <nist_symbol>Rn</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>227.035304</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-228</isotope>
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    <nist_symbol>Rn</nist_symbol>
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    <neutrons>142</neutrons>
    <relative_atomic_mass>228.037835</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-229</isotope>
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    <neutrons>143</neutrons>
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    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
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    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-230</isotope>
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    <nist_symbol>Rn</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>230.04514</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Rn-231</isotope>
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    <mass_number>231</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>231.04987</relative_atomic_mass>
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    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
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  <row>
    <isotope>Fr-199</isotope>
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    <mass_estimated>false</mass_estimated>
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  <row>
    <isotope>Fr-200</isotope>
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    <mass_number>200</mass_number>
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    <relative_atomic_mass>200.006586</relative_atomic_mass>
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    <mass_estimated>false</mass_estimated>
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  </row>
  <row>
    <isotope>Fr-201</isotope>
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    <relative_atomic_mass>201.003867</relative_atomic_mass>
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    <mass_estimated>false</mass_estimated>
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  <row>
    <isotope>Fr-202</isotope>
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    <mass_number>210</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>210.000494</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-211</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>211.0008932</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000085</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-212</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>211.999787</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-213</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>213.000384</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-214</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>214.0000997</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-215</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>215.0027204</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000082</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-216</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>216.0035334</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000094</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-217</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>217.0063207</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000092</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-218</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>218.007141</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-219</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>219.0100855</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-220</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>220.0110259</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-221</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>221.0139177</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-222</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>222.0153748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000049</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-223</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>223.0185023</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-224</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>224.020212</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-225</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>225</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>225.0236119</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-226</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>226</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>226.0254103</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-227</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>227.0291783</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-228</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>228</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>228.0310707</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-229</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>229</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>229.034942</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-230</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>230.037055</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-231</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>231</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>231.041027</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-232</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>232.0434753</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000098</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-233</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>233.047582</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-234</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>234.050342</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ra-235</isotope>
    <atomic_number>88</atomic_number>
    <element_symbol>Ra</element_symbol>
    <nist_symbol>Ra</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>235.05497</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[226]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-206</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>206</mass_number>
    <neutrons>117</neutrons>
    <relative_atomic_mass>206.014452</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000077</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-207</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>207</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>207.011966</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-208</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>208.01155</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00006</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-209</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>209.009495</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-210</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>210.009436</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000062</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-211</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>211.007732</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-212</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>212.007813</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-213</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>213.006609</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-214</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>214.006918</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-215</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>215.006475</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-216</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>216.008743</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-217</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>217.009344</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-218</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>218.011642</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-219</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>219.012421</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-220</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>220.0147549</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000066</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-221</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>221.015592</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-222</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>222.0178442</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-223</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>223.0191377</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-224</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>224.0217232</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-225</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>225</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>225.02323</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000053</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-226</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>226</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>226.0260984</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-227</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>227.0277523</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000025</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-228</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>228</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>228.0310215</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-229</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>229</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>229.032956</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-230</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>230.036327</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-231</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>231</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>231.038393</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-232</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>232.042034</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-233</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>233.044346</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-234</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>234.048139</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-235</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>235.05084</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-236</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>236.054988</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000041</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Ac-237</isotope>
    <atomic_number>89</atomic_number>
    <element_symbol>Ac</element_symbol>
    <nist_symbol>Ac</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>237.05827</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[227]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Th-208</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>208</mass_number>
    <neutrons>118</neutrons>
    <relative_atomic_mass>208.0179</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000036</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-209</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>209</mass_number>
    <neutrons>119</neutrons>
    <relative_atomic_mass>209.017753</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-210</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>210</mass_number>
    <neutrons>120</neutrons>
    <relative_atomic_mass>210.015094</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-211</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>211</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>211.014929</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-212</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>212.012988</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-213</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>213.013009</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-214</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>214.0115</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-215</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>215.0117248</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000095</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-216</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>216.011056</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-217</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>217.013117</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-218</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>218.013276</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-219</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>219.015537</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-220</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>220.015748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-221</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>221.018184</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-222</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>222.018469</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-223</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>223.0208119</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000099</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-224</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>224.021464</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-225</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>225</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>225.0239514</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-226</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>226</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>226.0249034</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-227</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>227.0277042</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-228</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>228</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>228.0287413</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-229</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>229</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>229.0317627</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-230</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>230.0331341</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-231</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>231</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>231.0363046</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-232</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>232.0380558</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-233</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>233.0415823</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-234</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>234.0436014</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-235</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>235.047255</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-236</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>236.049657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-237</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>237.053629</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-238</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>238.0565</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Th-239</isotope>
    <atomic_number>90</atomic_number>
    <element_symbol>Th</element_symbol>
    <nist_symbol>Th</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>239.06077</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>232.0377(4)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known</notes>
  </row>
  <row>
    <isotope>Pa-212</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>212</mass_number>
    <neutrons>121</neutrons>
    <relative_atomic_mass>212.023203</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-213</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>213</mass_number>
    <neutrons>122</neutrons>
    <relative_atomic_mass>213.021109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-214</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>214</mass_number>
    <neutrons>123</neutrons>
    <relative_atomic_mass>214.020918</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000082</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-215</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>215</mass_number>
    <neutrons>124</neutrons>
    <relative_atomic_mass>215.019183</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-216</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>216</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>216.019109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-217</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>217.018325</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-218</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>218.020059</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-219</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>219.019904</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-220</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>220.021705</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-221</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>221.021875</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-222</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>222.023784</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-223</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>223.023963</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-224</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>224.0256176</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000082</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-225</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>225</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>225.026131</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-226</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>226</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>226.027948</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-227</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>227.0288054</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000008</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-228</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>228</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>228.0310517</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-229</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>229</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>229.0320972</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-230</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>230.034541</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000035</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-231</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>231</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>231.0358842</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>1</natural_abundance>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-232</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>232.0385917</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000083</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-233</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>233.0402472</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-234</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>234.0433072</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-235</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>235.045399</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-236</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>236.048668</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-237</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>237.051023</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-238</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>238.054637</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-239</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>239.05726</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-240</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>240.06098</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pa-241</isotope>
    <atomic_number>91</atomic_number>
    <element_symbol>Pa</element_symbol>
    <nist_symbol>Pa</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>241.06408</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>231.03588(2)</standard_atomic_weight>
  </row>
  <row>
    <isotope>U-217</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>217</mass_number>
    <neutrons>125</neutrons>
    <relative_atomic_mass>217.02466</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-218</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>218</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>218.023523</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-219</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>219.024999</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-220</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>220.02462</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-221</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>221.02628</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-222</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>222.026</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-223</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>223.027739</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-224</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>224.027605</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-225</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>225</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>225.029391</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-226</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>226</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>226.029339</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-227</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>227.031157</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-228</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>228</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>228.031371</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-229</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>229</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>229.0335063</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-230</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>230.0339401</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-231</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>231</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>231.0362939</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000032</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-232</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>232.0371563</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-233</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>233.0396355</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-234</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>234.0409523</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.000054</natural_abundance>
    <natural_abundance_uncertainty>0.000005</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-235</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>235.0439301</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.007204</natural_abundance>
    <natural_abundance_uncertainty>0.000006</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-236</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>236.0455682</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-237</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>237.0487304</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-238</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>238.0507884</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <natural_abundance>0.992742</natural_abundance>
    <natural_abundance_uncertainty>0.00001</natural_abundance_uncertainty>
    <naturally_occurring>true</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-239</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>239.0542935</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-240</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>240.0565934</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-241</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>241.06033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-242</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>242.06293</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>U-243</isotope>
    <atomic_number>92</atomic_number>
    <element_symbol>U</element_symbol>
    <nist_symbol>U</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>243.06699</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>238.02891(3)</standard_atomic_weight>
    <notes>g: geologically exceptional specimens known; m: modified isotopic compositions in commercial material</notes>
  </row>
  <row>
    <isotope>Np-219</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>219</mass_number>
    <neutrons>126</neutrons>
    <relative_atomic_mass>219.03143</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-220</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>220</mass_number>
    <neutrons>127</neutrons>
    <relative_atomic_mass>220.03254</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-221</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>221</mass_number>
    <neutrons>128</neutrons>
    <relative_atomic_mass>221.03204</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-222</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>222</mass_number>
    <neutrons>129</neutrons>
    <relative_atomic_mass>222.0333</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-223</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>223</mass_number>
    <neutrons>130</neutrons>
    <relative_atomic_mass>223.03285</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-224</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>224</mass_number>
    <neutrons>131</neutrons>
    <relative_atomic_mass>224.03422</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-225</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>225</mass_number>
    <neutrons>132</neutrons>
    <relative_atomic_mass>225.033911</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-226</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>226</mass_number>
    <neutrons>133</neutrons>
    <relative_atomic_mass>226.035188</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000095</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-227</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>227</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>227.034957</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-228</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>228</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>228.036067</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-229</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>229</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>229.036264</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000093</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-230</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>230.037828</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-231</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>231</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>231.038245</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-232</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>232.04011</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-233</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>233.040741</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-234</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>234.0428953</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000091</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-235</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>235.0440635</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-236</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>236.04657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-237</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>237.0481736</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-238</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>238.0509466</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-239</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>239.0529392</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-240</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>240.056165</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000018</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-241</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>241.058253</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-242</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>242.06164</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-243</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>243.06428</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-244</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>244</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>244.06785</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Np-245</isotope>
    <atomic_number>93</atomic_number>
    <element_symbol>Np</element_symbol>
    <nist_symbol>Np</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>245.0708</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[237]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-228</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>228</mass_number>
    <neutrons>134</neutrons>
    <relative_atomic_mass>228.038732</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000033</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-229</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>229</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>229.040144</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000055</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-230</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>230.03965</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-231</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>231</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>231.041102</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000028</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-232</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>232.041185</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-233</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>233.042998</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-234</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>234.0433174</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-235</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>235.045286</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-236</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>236.0460581</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-237</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>237.0484098</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-238</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>238.0495601</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-239</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>239.0521636</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-240</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>240.0538138</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-241</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>241.0568517</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-242</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>242.0587428</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-243</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>243.0620036</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-244</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>244</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>244.0642053</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-245</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>245.067826</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-246</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>246</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>246.070205</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Pu-247</isotope>
    <atomic_number>94</atomic_number>
    <element_symbol>Pu</element_symbol>
    <nist_symbol>Pu</nist_symbol>
    <mass_number>247</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>247.07419</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
    <standard_atomic_weight>[244]</standard_atomic_weight>
  </row>
  <row>
    <isotope>Am-230</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>230</mass_number>
    <neutrons>135</neutrons>
    <relative_atomic_mass>230.04609</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-231</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>231</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>231.04556</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-232</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>232.04645</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-233</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>233.04644</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-234</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>234.04773</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00017</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-235</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>235.047908</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-236</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>236.04943</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-237</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>237.049996</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-238</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>238.051985</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-239</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>239.0530247</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-240</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>240.0553</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000015</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-241</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>241.0568293</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-242</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>242.0595494</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-243</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>243.0613813</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-244</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>244</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>244.0642851</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-245</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>245.0664548</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-246</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>246</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>246.069775</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-247</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>247</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>247.07209</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-248</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>248</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>248.07575</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Am-249</isotope>
    <atomic_number>95</atomic_number>
    <element_symbol>Am</element_symbol>
    <nist_symbol>Am</nist_symbol>
    <mass_number>249</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>249.07848</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-232</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>232</mass_number>
    <neutrons>136</neutrons>
    <relative_atomic_mass>232.04982</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-233</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>233</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>233.05077</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000077</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-234</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>234.05016</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-235</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>235.05154</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-236</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>236.051374</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-237</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>237.052869</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-238</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>238.053081</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-239</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>239.05491</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000058</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-240</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>240.0555297</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-241</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>241.0576532</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-242</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>242.058836</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-243</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>243.0613893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-244</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>244</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>244.0627528</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-245</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>245.0654915</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-246</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>246</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>246.0672238</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-247</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>247</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>247.0703541</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000047</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-248</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>248</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>248.0723499</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-249</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>249</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>249.0759548</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-250</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>250</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>250.078358</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-251</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>251</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>251.082286</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cm-252</isotope>
    <atomic_number>96</atomic_number>
    <element_symbol>Cm</element_symbol>
    <nist_symbol>Cm</nist_symbol>
    <mass_number>252</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>252.08487</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-234</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>234</mass_number>
    <neutrons>137</neutrons>
    <relative_atomic_mass>234.05727</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-235</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>235</mass_number>
    <neutrons>138</neutrons>
    <relative_atomic_mass>235.05658</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-236</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>236</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>236.05748</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-237</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>237.0571</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-238</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>238.0582</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00027</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-239</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>239.05824</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-240</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>240.05976</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00016</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-241</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>241.06016</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-242</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>242.06198</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-243</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>243.0630078</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000051</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-244</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>244</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>244.065181</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-245</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>245.0663618</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000024</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-246</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>246</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>246.068673</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000064</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-247</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>247</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>247.0703073</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000059</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-248</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>248</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>248.073088</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-249</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>249</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>249.0749877</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-250</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>250</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>250.0783167</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-251</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>251</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>251.080762</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-252</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>252</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>252.08431</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-253</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>253</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>253.08688</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bk-254</isotope>
    <atomic_number>97</atomic_number>
    <element_symbol>Bk</element_symbol>
    <nist_symbol>Bk</nist_symbol>
    <mass_number>254</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>254.0906</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-237</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>237</mass_number>
    <neutrons>139</neutrons>
    <relative_atomic_mass>237.062198</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000094</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-238</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>238</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>238.06149</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-239</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>239.06253</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00023</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-240</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>240.062256</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-241</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>241.06369</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-242</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>242.063754</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000014</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-243</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>243.06548</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-244</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>244</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>244.0660008</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-245</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>245.0680487</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-246</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>246</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>246.0688055</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-247</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>247</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>247.070965</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-248</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>248</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>248.0721851</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-249</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>249</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>249.0748539</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000023</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-250</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>250</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>250.0764062</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-251</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>251</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>251.0795886</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000048</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-252</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>252</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>252.0816272</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000056</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-253</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>253</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>253.0851345</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-254</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>254</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>254.087324</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000013</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-255</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>255</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>255.09105</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cf-256</isotope>
    <atomic_number>98</atomic_number>
    <element_symbol>Cf</element_symbol>
    <nist_symbol>Cf</nist_symbol>
    <mass_number>256</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>256.09344</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00034</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-239</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>239</mass_number>
    <neutrons>140</neutrons>
    <relative_atomic_mass>239.06823</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-240</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>240</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>240.06892</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-241</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>241.06856</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-242</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>242.06957</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00028</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-243</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>243.06951</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-244</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>244</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>244.07088</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-245</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>245.07125</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-246</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>246</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>246.0729</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-247</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>247</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>247.073622</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000021</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-248</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>248</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>248.075471</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000056</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-249</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>249</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>249.076411</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-250</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>250</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>250.07861</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-251</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>251</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>251.0799936</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000067</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-252</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>252</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>252.08298</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-253</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>253</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>253.0848257</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000027</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-254</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>254</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>254.0880222</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000045</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-255</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>255</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>255.090275</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-256</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>256</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>256.0936</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-257</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>257</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>257.09598</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00044</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Es-258</isotope>
    <atomic_number>99</atomic_number>
    <element_symbol>Es</element_symbol>
    <nist_symbol>Es</nist_symbol>
    <mass_number>258</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>258.09952</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-241</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>241</mass_number>
    <neutrons>141</neutrons>
    <relative_atomic_mass>241.07421</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-242</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>242</mass_number>
    <neutrons>142</neutrons>
    <relative_atomic_mass>242.07343</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00043</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-243</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>243</mass_number>
    <neutrons>143</neutrons>
    <relative_atomic_mass>243.07446</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00023</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-244</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>244</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>244.07404</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-245</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>245.07535</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00021</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-246</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>246</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>246.07535</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000017</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-247</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>247</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>247.07694</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-248</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>248</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>248.0771865</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000092</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-249</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>249</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>249.0789275</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000068</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-250</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>250</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>250.079521</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000086</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-251</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>251</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>251.08154</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-252</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>252</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>252.0824671</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000061</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-253</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>253</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>253.0851846</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000037</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-254</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>254</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>254.0868544</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000003</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-255</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>255</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>255.089964</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000052</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-256</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>256</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>256.0917745</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000078</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-257</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>257</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>257.0951061</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000069</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-258</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>258</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>258.09708</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-259</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>259</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>259.1006</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fm-260</isotope>
    <atomic_number>100</atomic_number>
    <element_symbol>Fm</element_symbol>
    <nist_symbol>Fm</nist_symbol>
    <mass_number>260</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>260.10281</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00055</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-245</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>245</mass_number>
    <neutrons>144</neutrons>
    <relative_atomic_mass>245.08081</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-246</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>246</mass_number>
    <neutrons>145</neutrons>
    <relative_atomic_mass>246.08171</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00028</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-247</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>247</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>247.08152</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-248</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>248</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>248.08282</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00026</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-249</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>249</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>249.08291</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-250</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>250</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>250.08441</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-251</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>251</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>251.084774</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-252</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>252</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>252.08643</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-253</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>253</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>253.087144</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-254</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>254</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>254.08959</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-255</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>255</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>255.0910841</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000073</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-256</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>256</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>256.09389</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-257</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>257</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>257.0955424</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000029</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-258</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>258</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>258.0984315</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000005</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-259</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>259</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>259.10051</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-260</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>260</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>260.10365</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00034</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-261</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>261</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>261.10583</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00062</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Md-262</isotope>
    <atomic_number>101</atomic_number>
    <element_symbol>Md</element_symbol>
    <nist_symbol>Md</nist_symbol>
    <mass_number>262</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>262.1091</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00045</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-248</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>248</mass_number>
    <neutrons>146</neutrons>
    <relative_atomic_mass>248.08655</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-249</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>249</mass_number>
    <neutrons>147</neutrons>
    <relative_atomic_mass>249.0878</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-250</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>250</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>250.08756</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-251</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>251</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>251.08894</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-252</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>252</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>252.088967</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00001</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-253</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>253</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>253.0905641</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000075</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-254</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>254</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>254.090956</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000011</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-255</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>255</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>255.093191</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000016</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-256</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>256</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>256.0942829</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000084</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-257</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>257</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>257.0968878</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0000074</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-258</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>258</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>258.09821</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-259</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>259</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>259.10103</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-260</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>260</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>260.10264</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-261</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>261</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>261.1057</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-262</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>262</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>262.10746</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-263</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>263</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>263.11071</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00053</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>No-264</isotope>
    <atomic_number>102</atomic_number>
    <element_symbol>No</element_symbol>
    <nist_symbol>No</nist_symbol>
    <mass_number>264</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>264.11273</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0007</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-251</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>251</mass_number>
    <neutrons>148</neutrons>
    <relative_atomic_mass>251.09418</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-252</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>252</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>252.09526</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00026</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-253</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>253</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>253.09509</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-254</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>254</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>254.09648</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-255</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>255</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>255.096562</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-256</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>256</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>256.098494</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000089</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-257</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>257</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>257.099418</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000047</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-258</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>258</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>258.10176</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00011</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-259</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>259</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>259.102902</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000076</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-260</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>260</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>260.1055</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-261</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>261</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>261.10688</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-262</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>262</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>262.10961</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-263</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>263</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>263.11136</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-264</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>264</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>264.1142</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00047</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-265</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>265</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>265.11619</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00065</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lr-266</isotope>
    <atomic_number>103</atomic_number>
    <element_symbol>Lr</element_symbol>
    <nist_symbol>Lr</nist_symbol>
    <mass_number>266</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>266.11983</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00056</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-253</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>253</mass_number>
    <neutrons>149</neutrons>
    <relative_atomic_mass>253.10044</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00044</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-254</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>254</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>254.10005</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-255</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>255</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>255.10127</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-256</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>256</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>256.101152</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000019</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-257</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>257</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>257.102918</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000012</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-258</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>258</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>258.103428</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-259</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>259</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>259.105596</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000078</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-260</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>260</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>260.10644</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-261</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>261</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>261.108773</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000054</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-262</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>262</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>262.10992</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-263</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>263</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>263.11249</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-264</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>264</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>264.11388</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-265</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>265</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>265.11668</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-266</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>266</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>266.11817</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0005</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-267</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>267</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>267.12179</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00062</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rf-268</isotope>
    <atomic_number>104</atomic_number>
    <element_symbol>Rf</element_symbol>
    <nist_symbol>Rf</nist_symbol>
    <mass_number>268</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>268.12397</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00077</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-255</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>255</mass_number>
    <neutrons>150</neutrons>
    <relative_atomic_mass>255.10707</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00045</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-256</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>256</mass_number>
    <neutrons>151</neutrons>
    <relative_atomic_mass>256.10789</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00026</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-257</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>257</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>257.10758</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-258</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>258</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>258.10928</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-259</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>259</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>259.109492</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000057</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-260</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>260</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>260.1113</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-261</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>261</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>261.11192</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00012</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-262</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>262</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>262.11407</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-263</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>263</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>263.11499</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-264</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>264</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>264.11741</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00025</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-265</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>265</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>265.11861</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00024</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-266</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>266</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>266.12103</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-267</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>267</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>267.12247</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00044</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-268</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>268</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>268.12567</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00057</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-269</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>269</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>269.12791</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00073</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Db-270</isotope>
    <atomic_number>105</atomic_number>
    <element_symbol>Db</element_symbol>
    <nist_symbol>Db</nist_symbol>
    <mass_number>270</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>270.13136</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-258</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>258</mass_number>
    <neutrons>152</neutrons>
    <relative_atomic_mass>258.11298</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00044</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-259</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>259</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>259.1144</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-260</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>260</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>260.114384</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000022</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-261</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>261</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>261.115949</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00002</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-262</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>262</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>262.116337</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000038</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-263</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>263</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>263.11829</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-264</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>264</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>264.11893</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-265</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>265</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>265.12109</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-266</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>266</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>266.12198</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00026</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-267</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>267</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>267.12436</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-268</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>268</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>268.12539</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0005</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-269</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>269</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>269.12863</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-270</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>270</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>270.13043</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0006</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-271</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>271</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>271.13393</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00063</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-272</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>272</mass_number>
    <neutrons>166</neutrons>
    <relative_atomic_mass>272.13589</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00083</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Sg-273</isotope>
    <atomic_number>106</atomic_number>
    <element_symbol>Sg</element_symbol>
    <nist_symbol>Sg</nist_symbol>
    <mass_number>273</mass_number>
    <neutrons>167</neutrons>
    <relative_atomic_mass>273.13958</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-260</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>260</mass_number>
    <neutrons>153</neutrons>
    <relative_atomic_mass>260.12166</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00026</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-261</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>261</mass_number>
    <neutrons>154</neutrons>
    <relative_atomic_mass>261.12145</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00022</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-262</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>262</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>262.12297</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-263</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>263</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>263.12292</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-264</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>264</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>264.12459</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00019</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-265</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>265</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>265.12491</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00025</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-266</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>266</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>266.12679</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-267</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>267</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>267.1275</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00028</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-268</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>268</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>268.12969</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00041</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-269</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>269</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>269.13042</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0004</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-270</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>270</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>270.13336</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00031</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-271</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>271</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>271.13526</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00048</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-272</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>272</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>272.13826</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00058</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-273</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>273</mass_number>
    <neutrons>166</neutrons>
    <relative_atomic_mass>273.14024</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0008</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-274</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>274</mass_number>
    <neutrons>167</neutrons>
    <relative_atomic_mass>274.14355</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00065</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Bh-275</isotope>
    <atomic_number>107</atomic_number>
    <element_symbol>Bh</element_symbol>
    <nist_symbol>Bh</nist_symbol>
    <mass_number>275</mass_number>
    <neutrons>168</neutrons>
    <relative_atomic_mass>275.14567</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-263</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>263</mass_number>
    <neutrons>155</neutrons>
    <relative_atomic_mass>263.12852</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-264</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>264</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>264.128357</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000031</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-265</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>265</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>265.129793</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000026</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-266</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>266</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>266.130046</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000042</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-267</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>267</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>267.13167</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-268</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>268</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>268.13186</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0003</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-269</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>269</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>269.13375</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00013</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-270</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>270</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>270.13429</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00027</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-271</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>271</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>271.13717</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-272</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>272</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>272.1385</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00055</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-273</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>273</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>273.14168</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0004</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-274</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>274</mass_number>
    <neutrons>166</neutrons>
    <relative_atomic_mass>274.1433</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00063</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-275</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>275</mass_number>
    <neutrons>167</neutrons>
    <relative_atomic_mass>275.14667</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00063</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-276</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>276</mass_number>
    <neutrons>168</neutrons>
    <relative_atomic_mass>276.14846</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00086</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Hs-277</isotope>
    <atomic_number>108</atomic_number>
    <element_symbol>Hs</element_symbol>
    <nist_symbol>Hs</nist_symbol>
    <mass_number>277</mass_number>
    <neutrons>169</neutrons>
    <relative_atomic_mass>277.1519</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00058</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-265</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>265</mass_number>
    <neutrons>156</neutrons>
    <relative_atomic_mass>265.136</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00048</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-266</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>266</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>266.13737</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00033</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-267</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>267</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>267.13719</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00054</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-268</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>268</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>268.13865</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00025</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-269</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>269</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>269.13882</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0005</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-270</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>270</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>270.14033</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00018</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-271</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>271</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>271.14074</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00035</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-272</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>272</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>272.14341</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00052</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-273</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>273</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>273.1444</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00052</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-274</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>274</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>274.14724</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00038</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-275</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>275</mass_number>
    <neutrons>166</neutrons>
    <relative_atomic_mass>275.14882</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0005</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-276</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>276</mass_number>
    <neutrons>167</neutrons>
    <relative_atomic_mass>276.15159</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00059</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-277</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>277</mass_number>
    <neutrons>168</neutrons>
    <relative_atomic_mass>277.15327</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00082</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-278</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>278</mass_number>
    <neutrons>169</neutrons>
    <relative_atomic_mass>278.15631</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00068</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mt-279</isotope>
    <atomic_number>109</atomic_number>
    <element_symbol>Mt</element_symbol>
    <nist_symbol>Mt</nist_symbol>
    <mass_number>279</mass_number>
    <neutrons>170</neutrons>
    <relative_atomic_mass>279.15808</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00072</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-267</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>267</mass_number>
    <neutrons>157</neutrons>
    <relative_atomic_mass>267.14377</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-268</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>268</mass_number>
    <neutrons>158</neutrons>
    <relative_atomic_mass>268.14348</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00032</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-269</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>269</mass_number>
    <neutrons>159</neutrons>
    <relative_atomic_mass>269.144752</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000034</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-270</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>270</mass_number>
    <neutrons>160</neutrons>
    <relative_atomic_mass>270.144584</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.000052</relative_atomic_mass_uncertainty>
    <mass_estimated>false</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-271</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>271</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>271.14595</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0001</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-272</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>272</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>272.14602</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00044</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-273</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>273</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>273.14856</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00014</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-274</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>274</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>274.14941</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00042</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-275</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>275</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>275.15203</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00045</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-276</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>276</mass_number>
    <neutrons>166</neutrons>
    <relative_atomic_mass>276.15303</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00059</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-277</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>277</mass_number>
    <neutrons>167</neutrons>
    <relative_atomic_mass>277.15591</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00041</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-278</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>278</mass_number>
    <neutrons>168</neutrons>
    <relative_atomic_mass>278.15704</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00067</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-279</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>279</mass_number>
    <neutrons>169</neutrons>
    <relative_atomic_mass>279.1601</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-280</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>280</mass_number>
    <neutrons>170</neutrons>
    <relative_atomic_mass>280.16131</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00089</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ds-281</isotope>
    <atomic_number>110</atomic_number>
    <element_symbol>Ds</element_symbol>
    <nist_symbol>Ds</nist_symbol>
    <mass_number>281</mass_number>
    <neutrons>171</neutrons>
    <relative_atomic_mass>281.16451</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00059</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-272</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>272</mass_number>
    <neutrons>161</neutrons>
    <relative_atomic_mass>272.15327</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00025</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-273</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>273</mass_number>
    <neutrons>162</neutrons>
    <relative_atomic_mass>273.15313</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00056</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-274</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>274</mass_number>
    <neutrons>163</neutrons>
    <relative_atomic_mass>274.15525</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00019</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-275</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>275</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>275.15594</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00056</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-276</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>276</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>276.15833</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00068</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-277</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>277</mass_number>
    <neutrons>166</neutrons>
    <relative_atomic_mass>277.15907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00061</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-278</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>278</mass_number>
    <neutrons>167</neutrons>
    <relative_atomic_mass>278.16149</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00038</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-279</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>279</mass_number>
    <neutrons>168</neutrons>
    <relative_atomic_mass>279.16272</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00051</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-280</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>280</mass_number>
    <neutrons>169</neutrons>
    <relative_atomic_mass>280.16514</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00061</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-281</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>281</mass_number>
    <neutrons>170</neutrons>
    <relative_atomic_mass>281.16636</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00089</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-282</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>282</mass_number>
    <neutrons>171</neutrons>
    <relative_atomic_mass>282.16912</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00072</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Rg-283</isotope>
    <atomic_number>111</atomic_number>
    <element_symbol>Rg</element_symbol>
    <nist_symbol>Rg</nist_symbol>
    <mass_number>283</mass_number>
    <neutrons>172</neutrons>
    <relative_atomic_mass>283.17054</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00079</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-276</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>276</mass_number>
    <neutrons>164</neutrons>
    <relative_atomic_mass>276.16141</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00064</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-277</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>277</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>277.16364</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00015</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-278</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>278</mass_number>
    <neutrons>166</neutrons>
    <relative_atomic_mass>278.16416</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00047</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-279</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>279</mass_number>
    <neutrons>167</neutrons>
    <relative_atomic_mass>279.16654</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0005</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-280</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>280</mass_number>
    <neutrons>168</neutrons>
    <relative_atomic_mass>280.16715</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00063</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-281</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>281</mass_number>
    <neutrons>169</neutrons>
    <relative_atomic_mass>281.16975</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00042</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-282</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>282</mass_number>
    <neutrons>170</neutrons>
    <relative_atomic_mass>282.1705</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0007</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-283</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>283</mass_number>
    <neutrons>171</neutrons>
    <relative_atomic_mass>283.17327</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00065</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-284</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>284</mass_number>
    <neutrons>172</neutrons>
    <relative_atomic_mass>284.17416</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00091</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Cn-285</isotope>
    <atomic_number>112</atomic_number>
    <element_symbol>Cn</element_symbol>
    <nist_symbol>Cn</nist_symbol>
    <mass_number>285</mass_number>
    <neutrons>173</neutrons>
    <relative_atomic_mass>285.17712</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0006</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-278</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>278</mass_number>
    <neutrons>165</neutrons>
    <relative_atomic_mass>278.17058</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0002</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-279</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>279</mass_number>
    <neutrons>166</neutrons>
    <relative_atomic_mass>279.17095</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-280</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>280</mass_number>
    <neutrons>167</neutrons>
    <relative_atomic_mass>280.17293</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-281</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>281</mass_number>
    <neutrons>168</neutrons>
    <relative_atomic_mass>281.17348</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-282</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>282</mass_number>
    <neutrons>169</neutrons>
    <relative_atomic_mass>282.17567</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00039</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-283</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>283</mass_number>
    <neutrons>170</neutrons>
    <relative_atomic_mass>283.17657</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00052</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-284</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>284</mass_number>
    <neutrons>171</neutrons>
    <relative_atomic_mass>284.17873</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00062</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-285</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>285</mass_number>
    <neutrons>172</neutrons>
    <relative_atomic_mass>285.17973</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00089</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-286</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>286</mass_number>
    <neutrons>173</neutrons>
    <relative_atomic_mass>286.18221</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00072</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Nh-287</isotope>
    <atomic_number>113</atomic_number>
    <element_symbol>Nh</element_symbol>
    <nist_symbol>Nh</nist_symbol>
    <mass_number>287</mass_number>
    <neutrons>174</neutrons>
    <relative_atomic_mass>287.18339</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00081</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fl-285</isotope>
    <atomic_number>114</atomic_number>
    <element_symbol>Fl</element_symbol>
    <nist_symbol>Fl</nist_symbol>
    <mass_number>285</mass_number>
    <neutrons>171</neutrons>
    <relative_atomic_mass>285.18364</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00047</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fl-286</isotope>
    <atomic_number>114</atomic_number>
    <element_symbol>Fl</element_symbol>
    <nist_symbol>Fl</nist_symbol>
    <mass_number>286</mass_number>
    <neutrons>172</neutrons>
    <relative_atomic_mass>286.18423</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00071</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fl-287</isotope>
    <atomic_number>114</atomic_number>
    <element_symbol>Fl</element_symbol>
    <nist_symbol>Fl</nist_symbol>
    <mass_number>287</mass_number>
    <neutrons>173</neutrons>
    <relative_atomic_mass>287.18678</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00066</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fl-288</isotope>
    <atomic_number>114</atomic_number>
    <element_symbol>Fl</element_symbol>
    <nist_symbol>Fl</nist_symbol>
    <mass_number>288</mass_number>
    <neutrons>174</neutrons>
    <relative_atomic_mass>288.18757</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00091</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Fl-289</isotope>
    <atomic_number>114</atomic_number>
    <element_symbol>Fl</element_symbol>
    <nist_symbol>Fl</nist_symbol>
    <mass_number>289</mass_number>
    <neutrons>175</neutrons>
    <relative_atomic_mass>289.19042</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0006</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mc-287</isotope>
    <atomic_number>115</atomic_number>
    <element_symbol>Mc</element_symbol>
    <nist_symbol>Mc</nist_symbol>
    <mass_number>287</mass_number>
    <neutrons>172</neutrons>
    <relative_atomic_mass>287.1907</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00052</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mc-288</isotope>
    <atomic_number>115</atomic_number>
    <element_symbol>Mc</element_symbol>
    <nist_symbol>Mc</nist_symbol>
    <mass_number>288</mass_number>
    <neutrons>173</neutrons>
    <relative_atomic_mass>288.19274</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00062</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mc-289</isotope>
    <atomic_number>115</atomic_number>
    <element_symbol>Mc</element_symbol>
    <nist_symbol>Mc</nist_symbol>
    <mass_number>289</mass_number>
    <neutrons>174</neutrons>
    <relative_atomic_mass>289.19363</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00089</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mc-290</isotope>
    <atomic_number>115</atomic_number>
    <element_symbol>Mc</element_symbol>
    <nist_symbol>Mc</nist_symbol>
    <mass_number>290</mass_number>
    <neutrons>175</neutrons>
    <relative_atomic_mass>290.19598</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00073</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Mc-291</isotope>
    <atomic_number>115</atomic_number>
    <element_symbol>Mc</element_symbol>
    <nist_symbol>Uup</nist_symbol>
    <mass_number>291</mass_number>
    <neutrons>176</neutrons>
    <relative_atomic_mass>291.19707</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00088</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lv-289</isotope>
    <atomic_number>116</atomic_number>
    <element_symbol>Lv</element_symbol>
    <nist_symbol>Lv</nist_symbol>
    <mass_number>289</mass_number>
    <neutrons>173</neutrons>
    <relative_atomic_mass>289.19816</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00057</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lv-290</isotope>
    <atomic_number>116</atomic_number>
    <element_symbol>Lv</element_symbol>
    <nist_symbol>Lv</nist_symbol>
    <mass_number>290</mass_number>
    <neutrons>174</neutrons>
    <relative_atomic_mass>290.19864</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00071</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lv-291</isotope>
    <atomic_number>116</atomic_number>
    <element_symbol>Lv</element_symbol>
    <nist_symbol>Lv</nist_symbol>
    <mass_number>291</mass_number>
    <neutrons>175</neutrons>
    <relative_atomic_mass>291.20108</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00066</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lv-292</isotope>
    <atomic_number>116</atomic_number>
    <element_symbol>Lv</element_symbol>
    <nist_symbol>Lv</nist_symbol>
    <mass_number>292</mass_number>
    <neutrons>176</neutrons>
    <relative_atomic_mass>292.20174</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00091</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Lv-293</isotope>
    <atomic_number>116</atomic_number>
    <element_symbol>Lv</element_symbol>
    <nist_symbol>Lv</nist_symbol>
    <mass_number>293</mass_number>
    <neutrons>177</neutrons>
    <relative_atomic_mass>293.20449</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.0006</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ts-291</isotope>
    <atomic_number>117</atomic_number>
    <element_symbol>Ts</element_symbol>
    <nist_symbol>Ts</nist_symbol>
    <mass_number>291</mass_number>
    <neutrons>174</neutrons>
    <relative_atomic_mass>291.20553</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00068</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ts-292</isotope>
    <atomic_number>117</atomic_number>
    <element_symbol>Ts</element_symbol>
    <nist_symbol>Ts</nist_symbol>
    <mass_number>292</mass_number>
    <neutrons>175</neutrons>
    <relative_atomic_mass>292.20746</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00075</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ts-293</isotope>
    <atomic_number>117</atomic_number>
    <element_symbol>Ts</element_symbol>
    <nist_symbol>Ts</nist_symbol>
    <mass_number>293</mass_number>
    <neutrons>176</neutrons>
    <relative_atomic_mass>293.20824</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00089</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Ts-294</isotope>
    <atomic_number>117</atomic_number>
    <element_symbol>Ts</element_symbol>
    <nist_symbol>Uus</nist_symbol>
    <mass_number>294</mass_number>
    <neutrons>177</neutrons>
    <relative_atomic_mass>294.21046</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00074</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Og-293</isotope>
    <atomic_number>118</atomic_number>
    <element_symbol>Og</element_symbol>
    <nist_symbol>Og</nist_symbol>
    <mass_number>293</mass_number>
    <neutrons>175</neutrons>
    <relative_atomic_mass>293.21356</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00078</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Og-294</isotope>
    <atomic_number>118</atomic_number>
    <element_symbol>Og</element_symbol>
    <nist_symbol>Og</nist_symbol>
    <mass_number>294</mass_number>
    <neutrons>176</neutrons>
    <relative_atomic_mass>294.21392</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00071</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
  <row>
    <isotope>Og-295</isotope>
    <atomic_number>118</atomic_number>
    <element_symbol>Og</element_symbol>
    <nist_symbol>Og</nist_symbol>
    <mass_number>295</mass_number>
    <neutrons>177</neutrons>
    <relative_atomic_mass>295.21624</relative_atomic_mass>
    <relative_atomic_mass_uncertainty>0.00069</relative_atomic_mass_uncertainty>
    <mass_estimated>true</mass_estimated>
    <naturally_occurring>false</naturally_occurring>
  </row>
</dataset>
