2
He
helium
4.0026

General properties

Group
group 18 (noble gases)
Period
period 1
Category
noble gases
Standard atomic weight
4.002 602(2)
Melting point
0.95 K (-272.20 °C)
Boiling point
4.222 K (-268.928 °C)
Phase at STP
gas

Additional properties

Block
s-block
Electron configuration
1s²
Electrons per shell
2
Electronegativity
–
Density
0.1786 g/L
Oxidation states
0
CAS Number
7440-59-7