Promethium vs Samarium
| Property | Pm Promethium | Sm Samarium |
|---|---|---|
| Atomic number | 61 | 62 |
| Symbol | Pm | Sm |
| Name | Promethium | Samarium |
| Category | lanthanide | lanthanide |
| Standard Atomic Weight | 145 u | 150.36 u |
| Period | 6 | 6 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s24f5 | [Xe]6s24f6 |
| Oxidation states | [2, 3] | [0, 1, 2, 3] |
| Electronegativity (Pauling) | N/A | 1.17 |
| Electron affinity | 0.129 eV | 0.156 eV |
| Density | 7260 kg/m³ | 7520 kg/m³ |
| Melting point | 1041.85 °C | 1073.85 °C |
| Boiling point | 2999.85 °C | 1793.85 °C |
| Discovery year | 1902 | 1878 |