Zirconium vs Promethium
| Property | Zr Zirconium | Pm Promethium |
|---|---|---|
| Atomic number | 40 | 61 |
| Symbol | Zr | Pm |
| Name | Zirconium | Promethium |
| Category | transition-metal | lanthanide |
| Standard Atomic Weight | 91.224 u | 145 u |
| Period | 5 | 6 |
| Group | 4 | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Kr]5s24d2 | [Xe]6s24f5 |
| Oxidation states | [1, 2, 3, 4] | [2, 3] |
| Electronegativity (Pauling) | 1.33 | N/A |
| Electron affinity | 0.426 eV | 0.129 eV |
| Density | 6520 kg/m³ | 7260 kg/m³ |
| Melting point | 1854.85 °C | 1041.85 °C |
| Boiling point | 4408.85 °C | 2999.85 °C |
| Discovery year | 1789 | 1902 |