Roentgenium (pronounced /rɛntˈɡɛniəm/ or /rʌntˈɡɛniəm/ ( listen)) is a synthetic radioactive chemical element with the symbol Rg and atomic number 111. It is placed as the heaviest member of the group 11 (IB) elements, although a sufficiently stable isotope is not known at this time that would allow its position as a heavier homologue of gold to be confirmed.
Roentgenium was first observed in 1994 and several isotopes have been synthesized since...
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Roentgenium (pronounced /rɛntˈɡɛniəm/ or /rʌntˈɡɛniəm/ ( listen)) is a synthetic radioactive chemical element with the symbol Rg and atomic number 111. It is placed as the heaviest member of the group 11 (IB) elements, although a sufficiently stable isotope is not known at this time that would allow its position as a heavier homologue of gold to be confirmed.
Roentgenium was first observed in 1994 and several isotopes have been synthesized since its first discovery. The most stable known isotope is Rg with a half-life of ~4 seconds.
Roentgenium was officially discovered by Peter Armbruster, Gottfried Münzenberg, and their team working at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany on December 8, 1994. Only three atoms of it were observed (all Rg), by the cold fusion between nickel ions and a bismuth target in a linear accelerator:
In 2001, the IUPAC/IUPAP Joint Working Party (JWP) concluded that there was insufficient evidence for the discovery at that...
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