Selenium vs Roentgenium
| Property | Se Selenium | Rg Roentgenium |
|---|---|---|
| Atomic number | 34 | 111 |
| Symbol | Se | Rg |
| Name | Selenium | Roentgenium |
| Category | nonmetal | transition-metal |
| Standard Atomic Weight | 78.971 u | 281 u |
| Period | 4 | 7 |
| Group | 16 | 11 |
| Block | p | s |
| Phase at STP | solid | N/A |
| Electron configuration | [Ar]4s23d104p4 | [Rn] 7s2 5f14 6d9(predicted) |
| Oxidation states | [-2, -1, 0, 1, 2, 3, 4, 5, 6] | [-1, 1, 3, 5] |
| Electronegativity (Pauling) | 2.55 | N/A |
| Electron affinity | 2.0206 eV | 1.6 eV |
| Density | 4809 kg/m³ | 2.870000e+4 kg/m³ |
| Melting point | 220.5 °C | -273.15 °C |
| Boiling point | 684.85 °C | -273.15 °C |
| Discovery year | 1817 | 1994 |