helium
Chemical element with symbol He and atomic number 2; rare gas; noble gas
Also known as element 2
- Symbol
- He
- Atomic number
- 2
- Mass
- 4.0026 Da
1
Sources- 1.Stated in Atomic weights of the elements 2013 (IUPAC Technical Report)Retrieved 2020-10-19
- 4.0026 Da
- Melting point
- -272.05°C
- , none
- , 0.95 K
- +1 more
- Boiling point
- -268.9°C
- , -452.07°F
- Density
- 0.1785 kg/m³
- Discovered by
- Discovered
- August 18, 1868
Overview
All data
173 statements · 24% with external sources · numbers in brackets are citations
- Subclass of
- nonmetal
- noble gases followed by: neon
- s-block
- Formula
- He
1
- He
- Canonical SMILES
- [He]
1
- [He]
- Refractive index
- 1 temperature: 0°C · under pressure: 1 standard atmosphere · wavelength: 589.29 nm
- Has characteristic
- colorlessness applies to part: simple substance
- tastelessness applies to part: simple substance
- odorlessness applies to part: simple substance
- diamagnetism
- Standard molar entropy
- 126 joule per mole kelvin state of matter: gas
- Part of
- period 1 follows: hydrogen
- noble gases followed by: neon
- Has use
- lifting gas
- coolant used by: nuclear reactor
- component part of: breathing gas · used by: technical diver
- food additive
- Thermal conductivity
- 0.1513 watt per metre kelvin
- Specific heat capacity
- 5,193 joule per kilogram kelvin
- Ionization energy
- 24.5874 eV
1
Sources- 1.“NIST Atomic Spectra Database, Ionization Energies”physics.nist.gov/asdRetrieved 2026-09-18
- 54.4178 eV
1
Sources- 1.“NIST Atomic Spectra Database, Ionization Energies”physics.nist.gov/asdRetrieved 2026-09-18
- 24.5874 eV
- IPA transcription
- ˈhiːliəm language: English
- Atomic radius
- 120 picometre
- Covalent radius
- 28 picometre
- Van der Waals radius
- 140 picometre
On other databases
97 identifiers linking helium across the web's reference databases
- Arabic Ontology lexical concept ID151078473
- ASHRAE refrigerant number704
- ATC codeV03AN03
- Australian Educational Vocabulary IDscot/3528
- BabelNet ID00006849n
- BBC Things ID227aaba8-a6f9-4974-bff3-3f71ed456870
- Bibliothèque nationale de France ID11978648w
- BNCF Thesaurus ID19752
- Brockhaus Enzyklopädie online IDhelium-20
- CAB ID178029
- CAMEO Chemicals ID3548
- CAS Registry Number7440-59-7
- ChEBI ID33681
- ChEMBL IDCHEMBL1796997
- ChemSpider ID22423
- COD ID9011639
- Common Procurement Vocabulary code24111300
- De Agostini IDèlio
- Dewey Decimal Classification553.971
- DrugBank IDDB09155
- DrugCentral ID4262
- DSSTOX compound identifierDTXCID5016402
- DSSTox substance IDDTXSID7036402
- E numberE939
- EC number231-168-5
- ECHA Substance Infocard ID100.028.334
- Encyclopædia Britannica Online IDscience/helium-chemical-element
- Encyclopædia Universalis IDhelium
- Encyclopedia of China (Third Edition) ID (2026)WqcZ3
- Encyclopedia of China (Third Edition) old ID (2021)298837
- Freebase ID/m/025rt79
- GND ID4132459-6
- Golden ID (archived)Helium-K8NB
- Great Norwegian Encyclopedia IDhelium
- Great Russian Encyclopedia portal IDgelii-9d40bf
- Harper's taghelium
- Hrvatska enciklopedija IDhelij
- HSDB ID553
- Human Metabolome Database IDHMDB0037238
- ICSC ID0603
- InChIInChI=1S/He
- InChIKeySWQJXJOGLNCZEY-UHFFFAOYSA-N
- Interlingual Index IDi113944
- J9U entity ID987007555644805171
- JSTOR topic ID (archived)helium
- KBpedia IDHelium
- Klexikon article IDHelium
- Krugosvet article (archived)nauka_i_tehnika/himiya/GELI.html
- Larousse IDdivers/hélium/57751
- Lex IDhelium
- Library of Congress Authorities IDsh85060043
- Lille norske leksikon IDhelium
- MeSH descriptor IDD006371
- MeSH tree codeD01.268.613.350
- Microsoft Academic ID (discontinued)546029482
- Mindat mineral ID25563
- NALT ID44987
- Namuwiki ID헬륨
- National Library of Poland MMS ID9810681063105606
- NDF-RT IDN0000147379
- NDL Authority ID00563132
- NE.se IDhelium
- NicoNicoPedia word article IDヘリウム
- NL CR AUT IDph503003
- OmegaWiki Defined Meaning7296
- Online PWN Encyclopedia ID3910758
- Open Library subject IDhelium
- OpenAlex IDC546029482
- Pixiv Encyclopedia IDヘリウム
- PM20 ware ID142944
- Probes And Drugs IDPD009020
- PSH ID5816
- PubChem CID23987
- Quora topic IDHelium
- RationalWiki IDHelium
- Römpp online IDRD-08-00783
- RxNorm CUI5140
- ScienceDirect topic IDchemistry/helium
- SureChEMBL ID27801530
- Treccani IDelio
- Treccani Vocabulary IDelio
- Treccani's Dizionario delle Scienze Fisiche IDelio
- Treccani's Enciclopedia Italiana IDelio
- U.S. National Archives Identifier10640583
- UK Parliament thesaurus ID455014
- UMLS CUIC0018880
- UniChem compound ID1097289
- UNII206GF3GB41
- USGS Thesaurus ID1470
- Vikidia article IDit:Elio