Inert, weightless and permanently escaping: helium is the only element that will not freeze at ordinary pressure, no matter how cold you make it.
- Atomic number
- 2
- Atomic mass
- 4.003 u
- Phase
- Gas
- Electron configuration
- 1s²
- Melting point
- 0.95 K · -272.2 °C
- Boiling point
- 4.22 K · -268.9 °C
- Density
- 0 g/cm³
- Electronegativity
- —
- Period / Group
- 1 / 18
- Discovery year
- 1868