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Author: Hans Lohninger

Atomic Number 111
Atomic Symbol Rg
CAS ID No. 54386-24-2
Atomic Weight [272] amu
Electron Configuration [Rn]7s1 5f14 6d10
Melting Point -
Boiling Point -
Density -

Roentgenium was discovered 1994 by a team led by S. Hofmann at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany. Only three atoms of it (all 272Rg) have been obtained by the fusion of nickel and bismuth in a linear accelerator:

209Bi + 64Ni 272Rg + 1 n

In 2001 the IUPAC concluded that there was insufficient evidence for the discovery in 1994. As a consequence the GSI team repeated their experiment in 2002 and detected a further 3 atoms. The name roentgenium (Rg) which has been proposed by the GSI team in honor of the German physicist Wilhelm Conrad Röntgen, has been accepted as a permanent name in 2004.

Last Update: 2011-02-16