Beryllium vs Promethium
| Property | Be Beryllium | Pm Promethium |
|---|---|---|
| Atomic number | 4 | 61 |
| Symbol | Be | Pm |
| Name | Beryllium | Promethium |
| Category | alkaline-earth-metal | lanthanide |
| Standard Atomic Weight | 9.012183 u | 145 u |
| Period | 2 | 6 |
| Group | 2 | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [He]2s2 | [Xe]6s24f5 |
| Oxidation states | [0, 1, 2] | [2, 3] |
| Electronegativity (Pauling) | 1.57 | N/A |
| Electron affinity | -0.52 eV | 0.129 eV |
| Density | 1850 kg/m³ | 7260 kg/m³ |
| Melting point | 1286.85 °C | 1041.85 °C |
| Boiling point | 2470.85 °C | 2999.85 °C |
| Discovery year | 1797 | 1902 |