Terbium vs Actinium
| Property | Tb Terbium | Ac Actinium |
|---|---|---|
| Atomic number | 65 | 89 |
| Symbol | Tb | Ac |
| Name | Terbium | Actinium |
| Category | lanthanide | actinide |
| Standard Atomic Weight | 158.92535 u | 227 u |
| Period | 6 | 7 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s24f9 | [Rn]7s26d1 |
| Oxidation states | [0, 1, 2, 3, 4] | [3] |
| Electronegativity (Pauling) | N/A | 1.1 |
| Electron affinity | 1.124 eV | 0.35 eV |
| Density | 8230 kg/m³ | 1.007000e+4 kg/m³ |
| Melting point | 1355.85 °C | 1050.85 °C |
| Boiling point | 3229.85 °C | 3197.85 °C |
| Discovery year | 1843 | 1899 |