Promethium vs Radon
| Property | Pm Promethium | Rn Radon |
|---|---|---|
| Atomic number | 61 | 86 |
| Symbol | Pm | Rn |
| Name | Promethium | Radon |
| Category | lanthanide | noble-gas |
| Standard Atomic Weight | 145 u | 222 u |
| Period | 6 | 6 |
| Group | N/A | 18 |
| Block | s | p |
| Phase at STP | solid | gas |
| Electron configuration | [Xe]6s24f5 | [Xe]6s24f145d106p6 |
| Oxidation states | [2, 3] | [0, 2, 6] |
| Electronegativity (Pauling) | N/A | N/A |
| Electron affinity | 0.129 eV | -0.7 eV |
| Density | 7260 kg/m³ | 9.73 kg/m³ |
| Melting point | 1041.85 °C | -71.15 °C |
| Boiling point | 2999.85 °C | -61.7 °C |
| Discovery year | 1902 | 1900 |