Promethium vs Einsteinium
| Property | Pm Promethium | Es Einsteinium |
|---|---|---|
| Atomic number | 61 | 99 |
| Symbol | Pm | Es |
| Name | Promethium | Einsteinium |
| Category | lanthanide | actinide |
| Standard Atomic Weight | 145 u | 252 u |
| Period | 6 | 7 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s24f5 | [Rn]7s25f11 |
| Oxidation states | [2, 3] | [2, 3, 4] |
| Electronegativity (Pauling) | N/A | 1.3 |
| Electron affinity | 0.129 eV | -0.3 eV |
| Density | 7260 kg/m³ | 8840 kg/m³ |
| Melting point | 1041.85 °C | 859.85 °C |
| Boiling point | 2999.85 °C | -273.15 °C |
| Discovery year | 1902 | 1952 |