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. One cannot speculate on whether it would be colored like gold or not.

History

It was first created at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany on December 8, 1994. Only three atoms of it have been created (all ²⁷²Rg), by the fusion of bismuth-209 and nickel-64 in a linear accelerator. (Nickel was bombarded onto the 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

• WebElements.com - Roentgenium
• IUPAC: Proposal of name roentgenium for element 111
• IUPAC: Element 111 is named roentgenium
• Apsidium - Roentgenium Element 111