Periodic table of the elements
HydrogenHeliumLithium
2
He
Helium
4.002602
2
2
He
Helium
4.002602
2
General
NameHelium
SymbolHe
Number2
Chemical seriesNoble gases
Group / Period18 / 1
Blocks-block
CAS registry number7440-59-7

Physical properties
Stategas
Density0.1786 g/L
Melting point0.95 K (−272.2 °C, −458.0 °F)
Boiling point4.22 K (−268.93 °C, −452.07 °F)
Critical point5.19 K, 0.227 MPa

Atomic properties
Atomic Weight4.002602 g/mol
Crystal structurecubic body centered
Electronegativity
Atomic radius128 pm
Atomic radius (calculated)31 pm
Electron configuration1s2
Electrons per shell2
Number of protons2
Number of neutrons2

Other languages
SpanishHelio
PortugueseHélio
FrenchHélium
GermanHelium
ItalianElio
RussianГелий
PolishHel
Chinese
Arabicهيليوم
TurkishHelyum
DutchHelium


Periodic table of the elements
HydrogenHeliumLithium