Promethium vs Thallium
| Property | Pm Promethium | Tl Thallium |
|---|---|---|
| Atomic number | 61 | 81 |
| Symbol | Pm | Tl |
| Name | Promethium | Thallium |
| Category | lanthanide | post-transition-metal |
| Standard Atomic Weight | 145 u | 204.3835 u |
| Period | 6 | 6 |
| Group | N/A | 13 |
| Block | s | p |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s24f5 | [Xe]6s24f145d106p1 |
| Oxidation states | [2, 3] | [-5, -2, -1, 1, 2, 3] |
| Electronegativity (Pauling) | N/A | 1.62 |
| Electron affinity | 0.129 eV | 0.377 eV |
| Density | 7260 kg/m³ | 1.180000e+4 kg/m³ |
| Melting point | 1041.85 °C | 303.85 °C |
| Boiling point | 2999.85 °C | 1472.85 °C |
| Discovery year | 1902 | 1861 |