Promethium vs Terbium
| Property | Pm Promethium | Tb Terbium |
|---|---|---|
| Atomic number | 61 | 65 |
| Symbol | Pm | Tb |
| Name | Promethium | Terbium |
| Category | lanthanide | lanthanide |
| Standard Atomic Weight | 145 u | 158.92535 u |
| Period | 6 | 6 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s24f5 | [Xe]6s24f9 |
| Oxidation states | [2, 3] | [0, 1, 2, 3, 4] |
| Electronegativity (Pauling) | N/A | N/A |
| Electron affinity | 0.129 eV | 1.124 eV |
| Density | 7260 kg/m³ | 8230 kg/m³ |
| Melting point | 1041.85 °C | 1355.85 °C |
| Boiling point | 2999.85 °C | 3229.85 °C |
| Discovery year | 1902 | 1843 |