Erbium vs Roentgenium
| Property | Er Erbium | Rg Roentgenium |
|---|---|---|
| Atomic number | 68 | 111 |
| Symbol | Er | Rg |
| Name | Erbium | Roentgenium |
| Category | lanthanide | transition-metal |
| Standard Atomic Weight | 167.259 u | 281 u |
| Period | 6 | 7 |
| Group | N/A | 11 |
| Block | s | s |
| Phase at STP | solid | N/A |
| Electron configuration | [Xe]6s24f12 | [Rn] 7s2 5f14 6d9(predicted) |
| Oxidation states | [0, 1, 2, 3] | [-1, 1, 3, 5] |
| Electronegativity (Pauling) | 1.24 | N/A |
| Electron affinity | 0.312 eV | 1.6 eV |
| Density | 9070 kg/m³ | 2.870000e+4 kg/m³ |
| Melting point | 1528.85 °C | -273.15 °C |
| Boiling point | 2867.85 °C | -273.15 °C |
| Discovery year | 1843 | 1994 |