Roentgenium

Unknown properties · atomic number 111

111282RgRoentgeniumSolidUnknown properties

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.

Properties of Roentgenium

Element category	Unknown properties
Atomic number	111
Atomic mass	282 u
Phase at STP	Solid
Group	11
Period	7
Block	d
Electron configuration	*[Rn] 5f14 6d10 7s1
Electrons per shell	2, 8, 18, 32, 32, 17, 2
Density	28.7 g/cm3
Discovered by	Gesellschaft für Schwerionenforschung

← Darmstadtium · Periodic table · Copernicium → Cn

About the unknown properties group

Superheavy synthetic elements made atom-by-atom, existing for fractions of a second; their true chemistry is still unmeasured.

Data: Periodic-Table-JSON (CC BY-SA 3.0) · stored statically on our server. https://en.wikipedia.org/wiki/Roentgenium

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🧪 Unknown properties

8 elements: Superheavy synthetic elements made atom-by-atom, existing for fractions of a second; their true chemistry is still unmeasured.