Helium |
Symbol | He |
---|---|
Latin name | Helium |
Atomic number | 2 |
Period | 1 |
Element category | Noble gases |
Relative atomic mass | 4.002602 |
Group | VIII.A |
Electron configuration | 1s2 |
Density [g/cm3] | 0.0001785 |
State | Gas |
Melting point [°C] | -272.12 |
Boiling point [°C] | -266.934 |
Critical point [°C] | -267.96 |
Critical pressure [MPa] | 0.227 |
Atomic radius [pm] | 31 |
Covalent radius [pm] | 32 |
Thermal conductivity [W m-1K-1] | 0.152 |
Heat capacity [J K-1g-1] | 5.193 |
Discovery | 1868 |
Stable isotopes | 2 |
Unstable isotopes | 2 |