Roentgenium (Rg)
Roentgenium (Rg) is element 111 of the periodic table, a transition metal in period 7 and group 11. It has no stable isotope and no standard atomic weight; 282 is the mass number of its longest-lived isotope. Its properties are predicted rather than measured: it is expected to be a solid at room temperature.
| Atomic number | 111 |
|---|---|
| Symbol | Rg |
| Standard atomic weight | [282] (mass number of the longest-lived isotope) |
| Molar mass | [282] g/mol |
| Category | Transition metal |
| Group | 11 |
| Period | 7 |
| Block | d-block |
| Electron configuration | [Rn] 7s2 5f14 6d9 (predicted) |
| Oxidation states | +5, +3, +1, −1 |
| Electronegativity (Pauling) | — |
| Atomic radius (van der Waals) | — |
| First ionisation energy | — |
| Electron affinity | — |
| State at room temperature | Solid (predicted) |
| Melting point | — |
| Boiling point | — |
| Density | — |
| Discovered | 1994 |
Group 11
Calculate with Roentgenium
Atomic weight: IUPAC CIAAW — no standard atomic weight; mass number in brackets. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.