| Property | Value |
|---|---|
| Atomic number | 2 |
| Atomic weight | 4.0026022 amu |
| Element family | Nobel gases |
| Electronic configuration | 1s2 |
| Stable and very long lived isotopes | 3He: 0.000138%, 4He: 99.999862% |
| Previous element | Hydrogen |
| Next element | Lithium |
| Density | 0.0001785 g/cm3 (STP) |
| Melting | -272.2 °C |
| Boiling | -268.9 °C |
| Covalent radius | 0.46 Å |
| Van der Waals radius | 1.4 Å |
| First ionization potential | 24.587 eV |
| Electron affinity | -0.500 eV |
| Discovery year | 1868 |
Helium is an element number 2 from nobel gases family. Its symbol is He. Helium atomic weight is 4.0026022 amu. He stable and long lived isotopes are 3He: 0.000138%, 4He: 99.999862%. Helium electronic configuration is 1s2. Sample compounds that contain Helium are He2, HHe, He3, He4, HeO2, HeO.
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