The Periodic Table of Elements
2
He
Helium
4.002602(2) amu
Additional Information:
| State | Group Block | Density | Atomic Radius | Electron Affinity | Ionization Energy | Melting Point | Boiling Point | Year Discovered |
|---|---|---|---|---|---|---|---|---|
| gas | noble gas | 0.0001785 kg/L | 32 pm | 0 | 2372 kJ/mol | °K | 4 °K | 1868 |
