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 |