Strontium vs Promethium
| Property | Sr Strontium | Pm Promethium |
|---|---|---|
| Atomic number | 38 | 61 |
| Symbol | Sr | Pm |
| Name | Strontium | Promethium |
| Category | alkaline-earth-metal | lanthanide |
| Standard Atomic Weight | 87.62 u | 145 u |
| Period | 5 | 6 |
| Group | 2 | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Kr]5s2 | [Xe]6s24f5 |
| Oxidation states | [1, 2] | [2, 3] |
| Electronegativity (Pauling) | 0.95 | N/A |
| Electron affinity | 0.052 eV | 0.129 eV |
| Density | 2640 kg/m³ | 7260 kg/m³ |
| Melting point | 776.85 °C | 1041.85 °C |
| Boiling point | 1381.85 °C | 2999.85 °C |
| Discovery year | 1792 | 1902 |