Lanthanum vs Promethium
| Property | La Lanthanum | Pm Promethium |
|---|---|---|
| Atomic number | 57 | 61 |
| Symbol | La | Pm |
| Name | Lanthanum | Promethium |
| Category | lanthanide | lanthanide |
| Standard Atomic Weight | 138.90547 u | 145 u |
| Period | 6 | 6 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s25d1 | [Xe]6s24f5 |
| Oxidation states | [0, 1, 2, 3] | [2, 3] |
| Electronegativity (Pauling) | 1.1 | N/A |
| Electron affinity | 0.47 eV | 0.129 eV |
| Density | 6150 kg/m³ | 7260 kg/m³ |
| Melting point | 917.85 °C | 1041.85 °C |
| Boiling point | 3463.85 °C | 2999.85 °C |
| Discovery year | 1839 | 1902 |