Promethium vs Hafnium
| Property | Pm Promethium | Hf Hafnium |
|---|---|---|
| Atomic number | 61 | 72 |
| Symbol | Pm | Hf |
| Name | Promethium | Hafnium |
| Category | lanthanide | transition-metal |
| Standard Atomic Weight | 145 u | 178.49 u |
| Period | 6 | 6 |
| Group | N/A | 4 |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s24f5 | [Xe]6s24f145d2 |
| Oxidation states | [2, 3] | [-2, 0, 1, 2, 3, 4] |
| Electronegativity (Pauling) | N/A | 1.3 |
| Electron affinity | 0.129 eV | 0.178 eV |
| Density | 7260 kg/m³ | 1.330000e+4 kg/m³ |
| Melting point | 1041.85 °C | 2232.85 °C |
| Boiling point | 2999.85 °C | 4602.85 °C |
| Discovery year | 1902 | 1911 |