'roentgenium' definitions:
Definition of 'roentgenium'
From: WordNet
noun
Definition of 'roentgenium'
From: Elements
- Symbol: Rg
- Atomic number: 111
- Atmic weight: 280
- Roentgenium 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 280Rg with a half-life of ~4 seconds. Roentgenium was officially discovered by Peter Armbruster, Gottfried M�nzenberg, and their team working at the Gesellschaft f�r Schwerionenforschung (GSI) in Darmstadt, Germany on December 8, 1994. Only three atoms of it were observed (all 272Rg), 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 moment in time. The GSI team repeated their experiment in 2000 and detected a further 3 atoms. In their 2003 report, the JWP decided that the GSI team should be acknowledged as the discoverers. The name roentgenium (Rg) was proposed by the GSI team in honor of the German physicist Wilhelm Conrad R�ntgen, and was accepted as a permanent name on November 1, 2004. Previously the element was known under the temporary IUPAC systematic element name unununium, Uuu.