Promethium vs Radium
| Property | Pm Promethium | Ra Radium |
|---|---|---|
| Atomic number | 61 | 88 |
| Symbol | Pm | Ra |
| Name | Promethium | Radium |
| Category | lanthanide | alkaline-earth-metal |
| Standard Atomic Weight | 145 u | 226 u |
| Period | 6 | 7 |
| Group | N/A | 2 |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s24f5 | [Rn]7s2 |
| Oxidation states | [2, 3] | [2] |
| Electronegativity (Pauling) | N/A | 0.9 |
| Electron affinity | 0.129 eV | 0.096 eV |
| Density | 7260 kg/m³ | 5000 kg/m³ |
| Melting point | 1041.85 °C | 699.85 °C |
| Boiling point | 2999.85 °C | 1139.85 °C |
| Discovery year | 1902 | 1898 |