Roentgenium (Rg)
Unknown / predicted · d-block · period 7 · group 11
Never seen.
Roentgenium (symbol Rg) is chemical element number 111, a unknown / predicted in group 11, period 7 of the periodic table. Its standard atomic weight is (282) and its electron configuration is [Rn] 5f14 6d9 7s2. Its state at room temperature is unknown, and it is radioactive. Named after Wilhelm Röntgen, discoverer of X-rays.
Properties
| Atomic number | 111 |
|---|---|
| Atomic mass | (282) |
| Category | Unknown / predicted |
| Block | d-block |
| Group · Period | 11 · 7 |
| Electron configuration | [Rn] 5f14 6d9 7s2 |
| Electrons per shell | 2, 8, 18, 32, 32, 17, 2 |
| State at 25 °C | unknown |
| Melting point | — |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | — |
| Radioactive | Yes — no stable isotope |
| Origin | synthetic |
| Discovered | 1994 · GSI Darmstadt |
Key facts about Roentgenium
- Named after Wilhelm Röntgen, discoverer of X-rays.
- Sits below silver and gold, and is predicted to be even less reactive than gold.
- Some calculations suggest it could form a stable negative ion, unlike any normal metal.
- Longest-lived isotope lasts about two minutes.
What Roentgenium is used for
None — research only.
Where it sits in the periodic table
Roentgenium is in group 11, period 7, of the d-block. Its electron configuration [Rn] 5f14 6d9 7s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Roentgenium on the interactive table →
Roentgenium — frequently asked questions
What is Roentgenium used for?
None — research only.
Is Roentgenium radioactive?
Yes. Roentgenium has no stable isotope, so every form of it is radioactive.
What is the electron configuration of Roentgenium?
Roentgenium has the electron configuration [Rn] 5f14 6d9 7s2, which is 2, 8, 18, 32, 32, 17, 2 electrons per shell.
What group and period is Roentgenium in?
Roentgenium is in group 11, period 7, in the d-block. Its outer shell holds 2 electrons.
Who discovered Roentgenium?
Roentgenium was discovered in 1994 by GSI Darmstadt.