Helium vs Plutonium
| Property | He Helium | Pu Plutonium |
|---|---|---|
| Atomic number | 2 | 94 |
| Symbol | He | Pu |
| Name | Helium | Plutonium |
| Category | noble-gas | actinide |
| Standard Atomic Weight | 4.002602 u | 244 u |
| Period | 1 | 7 |
| Group | 18 | N/A |
| Block | s | s |
| Phase at STP | gas | solid |
| Electron configuration | 1s2 | [Rn]7s25f6 |
| Oxidation states | [0] | [2, 3, 4, 5, 6, 7, 8] |
| Electronegativity (Pauling) | N/A | 1.28 |
| Electron affinity | -0.5 eV | -0.5 eV |
| Density | 0.1785 kg/m³ | 1.984000e+4 kg/m³ |
| Melting point | -272.2 °C | 639.85 °C |
| Boiling point | -268.93 °C | 3227.85 °C |
| Discovery year | 1868 | 1941 |