Actinium vs Meitnerium
| Property | Ac Actinium | Mt Meitnerium |
|---|---|---|
| Atomic number | 89 | 109 |
| Symbol | Ac | Mt |
| Name | Actinium | Meitnerium |
| Category | actinide | transition-metal |
| Standard Atomic Weight | 227 u | 278 u |
| Period | 7 | 7 |
| Group | N/A | 9 |
| Block | s | s |
| Phase at STP | solid | N/A |
| Electron configuration | [Rn]7s26d1 | [Rn]7s25f146d7(calculated) |
| Oxidation states | [3] | [1, 3, 4, 6, 8, 9] |
| Electronegativity (Pauling) | 1.1 | N/A |
| Electron affinity | 0.35 eV | 1.7 eV |
| Density | 1.007000e+4 kg/m³ | 3.740000e+4 kg/m³ |
| Melting point | 1050.85 °C | -273.15 °C |
| Boiling point | 3197.85 °C | -273.15 °C |
| Discovery year | 1899 | 1982 |