Lithium vs Promethium
| Property | Li Lithium | Pm Promethium |
|---|---|---|
| Atomic number | 3 | 61 |
| Symbol | Li | Pm |
| Name | Lithium | Promethium |
| Category | alkali-metal | lanthanide |
| Standard Atomic Weight | 6.9675 u | 145 u |
| Period | 2 | 6 |
| Group | 1 | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [He]2s1 | [Xe]6s24f5 |
| Oxidation states | [1] | [2, 3] |
| Electronegativity (Pauling) | 0.98 | N/A |
| Electron affinity | 0.61804 eV | 0.129 eV |
| Density | 534 kg/m³ | 7260 kg/m³ |
| Melting point | 180.5 °C | 1041.85 °C |
| Boiling point | 1341.85 °C | 2999.85 °C |
| Discovery year | 1817 | 1902 |