Roentgenium
Element 111 · Transition Metal
Roentgenium is the group 11 transactinide, the superheavy counterpart of gold. First made in 1994 at GSI Darmstadt, only a small number of atoms have ever been observed, decaying in milliseconds. Theory predicts it will be more reactive than gold because relativistic effects destabilize its outer electrons. No chemistry has been measured; all properties are predicted, with essentially no experimental data. Roentgenium is extremely radioactive, decaying within milliseconds.
Key facts
| Atomic number | 111 |
|---|---|
| Atomic weight | [282] |
| Category | Transition Metal |
| Group / Period | 11 / 7 |
| Block | d |
| Electron configuration | [Rn] 5f14 6d9 7s2 (predicted) |
| Common oxidation states | +3 (predicted) |
| State at STP | Solid |
Occurrence
Roentgenium is entirely synthetic, produced by fusing bismuth-209 with nickel-64.
Applications
Theoretical studies of relativistic chemistry
Future single-atom experiments (not yet achieved)
No commercial applications
Common compounds
- Roentgenium compounds (predicted, none observed)
Roentgenium is named after Wilhelm Rontgen, discoverer of X-rays, continuing the tradition of honoring physics pioneers.
Data source: IUPAC standard atomic weights 2021