111
Rg
Roentgenium
282
Roentgenium (Rg)
Transition MetalGroup 11Period 7d-block-blockRadioactive
Roentgenium is a chemical element with symbol Rg and atomic number 111. It is an extremely radioactive synthetic element (an element that can be created in a laboratory but is not found in nature); the most stable known isotope, roentgenium-282, has a half-life of 2.1 minutes. Roentgenium was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany.
Latin name: Roentgenium
Atomic Number
111
Atomic Mass
282 g/mol
Phase (STP)
Solid (predicted)
Electron Config.
[Rn] 5f¹⁴ 6d¹⁰ 7s¹
General
SymbolRg
Atomic Number111
Atomic Mass282 g/mol
CategoryTransition Metal
Group11
Period7
Blockd-block
Electron Configuration[Rn] 5f¹⁴ 6d¹⁰ 7s¹
Valence Electrons11
Colourgolden (predicted)
Physical Properties
Phase (STP)Solid (predicted)
Density28 (predicted)
Melting PointUnknown (predicted ~1900)
Boiling PointUnknown
Atomic Properties
Atomic Radius236 pm
Oxidation States+1, +3
Ion ChargeRg+/Rg3+
Nuclear & Hazards
RadioactiveYes
Half-life26 seconds (Rg-282)
Abundance
In Earth's Crust0%
Discovery & History
Discovery Year1994
Discovered ByGesellschaft für Schwerionenforschung (GSI), Darmstadt
Country of DiscoveryGermany
Isotopes of Roentgenium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Rg-280 | — | ~3.6 seconds | α |
| Rg-282 | — | ~2.1 minutes | α |