111[282]RgRoentgenium
Roentgenium (Rg) — element 111transition metal · group 11, period 7
Roentgenium is a chemical element with the symbol Rg and atomic number 111. It is a transition metal in group 11, period 7 of the periodic table (the d-block), with a standard atomic mass of [282] u. At room temperature (25 °C) roentgenium is predicted to be of unknown state.
💡 Known for: Named after Wilhelm Röntgen, who discovered X-rays.
# Roentgenium properties
| Symbol | Rg |
|---|---|
| Atomic number | 111 |
| Atomic mass | [282] u |
| Category | transition metal |
| Group | 11 |
| Period | 7 |
| Block | d-block |
| Electron configuration | [Rn] 5f¹⁴ 6d⁹ 7s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d⁹ 7s² |
| Electrons per shell | 2, 8, 18, 32, 32, 17, 2 |
| Protons / electrons | 111 / 111 |
| State at 25 °C | unknown |
| Melting point | unknown |
| Boiling point | unknown |
| Density | 28.7 g/cm³ (predicted) |
| Electronegativity (Pauling) | — |
| First ionization energy | — |
| Atomic radius | — |
| Discovered | 1994 |
Values for superheavy elements are theoretical predictions; none have been measured in bulk.
# Electron configuration of roentgenium
The electron configuration of roentgenium is [Rn] 5f¹⁴ 6d⁹ 7s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d⁹ 7s². Its 111 electrons fill 7 shells as 2, 8, 18, 32, 32, 17, 2, so the outermost shell holds 2 electrons. Because only a few atoms have ever been made, this configuration is a theoretical prediction.
# Related elements
DsDarmstadtiumprevious elementCnCoperniciumnext elementCuCoppergroup 11AgSilvergroup 11AuGoldgroup 11ScScandiumtransition metalTiTitaniumtransition metalVVanadiumtransition metalCrChromiumtransition metalMnManganesetransition metalFeIrontransition metalCoCobalttransition metalNiNickeltransition metal
# Roentgenium FAQ
What is the atomic number of roentgenium?
The atomic number of roentgenium is 111: every roentgenium atom has 111 protons in its nucleus. Its symbol is Rg.
What is the atomic mass of roentgenium?
The standard atomic mass of roentgenium is [282] u (the mass number of its longest-lived isotope, since it has no stable isotopes).
What is the electron configuration of roentgenium?
Roentgenium's electron configuration is [Rn] 5f¹⁴ 6d⁹ 7s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d⁹ 7s²), with 2, 8, 18, 32, 32, 17, 2 electrons per shell.
Is roentgenium a metal?
Yes. Roentgenium is a transition metal, one of the metals.
What is the melting point of roentgenium?
The melting point of roentgenium is not known. These values are predictions.
What is roentgenium used for / known for?
Named after Wilhelm Röntgen, who discovered X-rays.