Promethium vs Meitnerium
| Property | Pm Promethium | Mt Meitnerium |
|---|---|---|
| Atomic number | 61 | 109 |
| Symbol | Pm | Mt |
| Name | Promethium | Meitnerium |
| Category | lanthanide | transition-metal |
| Standard Atomic Weight | 145 u | 278 u |
| Period | 6 | 7 |
| Group | N/A | 9 |
| Block | s | s |
| Phase at STP | solid | N/A |
| Electron configuration | [Xe]6s24f5 | [Rn]7s25f146d7(calculated) |
| Oxidation states | [2, 3] | [1, 3, 4, 6, 8, 9] |
| Electronegativity (Pauling) | N/A | N/A |
| Electron affinity | 0.129 eV | 1.7 eV |
| Density | 7260 kg/m³ | 3.740000e+4 kg/m³ |
| Melting point | 1041.85 °C | -273.15 °C |
| Boiling point | 2999.85 °C | -273.15 °C |
| Discovery year | 1902 | 1982 |