Template:Elementbox header Template:Elementbox series Template:Elementbox groupperiodblock Template:Elementbox appearance Template:Elementbox atomicmass gpm Template:Elementbox econfig Template:Elementbox epershell Template:Elementbox phase Template:Elementbox cas number Template:Elementbox footer
Roentgenium (former temporary name: unununium or eka-gold) is a chemical element in the periodic table that has the symbol Rg (formerly temporarily Uuu) and atomic number 111 making it one of the super-heavy atoms. It is a synthetic element whose longest-lived isotope has a mass of 280 and a half-life of 3.6 seconds. Due to its presence in Group 11 it is a transition metal and so probably would appear as a heavy, solid, shiny metal. Due to a relativistic effect, it should be colored like gold.
History
It was first created at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany on December 8, 1994. Only three atoms of it were observed (all 272Rg), by the fusion of bismuth-209 and nickel-64 in a linear accelerator. (Nickel was bombarded onto the bismuth target.)
The name roentgenium was accepted as a permanent name on November 1 2004 in honour of Wilhelm Roentgen; before this date, the element was known under the temporary IUPAC systematic element name unununium. Some research has referred to it as "eka-gold".
Isotopes
Three isotopes of roentgenium are known. The longest-lived of these is 280Rg which decays through alpha decay and has a half-life of 3.6 s. the shortest-lived isotope is 272Rg which decays through alpha decay and has a half life of 1.5 ms. The other known isotope; 279Rg decays through alpha decay and has a half-life of 170 ms.
External links
