Roentgenium

darmstadtium – roentgenium – ununbium Au Rg         Full table
Known properties
Name, Symbol, Number	roentgenium, Rg, 111
Chemical series	Transition metals
Group, Period, Block	11, 7 , d
Appearance	unknown; probably metallic, silvery white or gray
Atomic weight	[272] amu
Electron configuration	probably [Rn]5f14 6d10 7s1
e- 's per energy level	2, 8, 18, 32, 32, 18, 1
State of matter	Presumably a solid

Roentgenium (former temporary name: unununium) is a chemical element in the periodic table that has the symbol Rg (formerly temporarily Uuu) and atomic number 111. It has an atomic weight of 272 making it one of the super-heavy atoms. It is a synthetic element whose only known isotope has a half-life of around 15 ms before it decays into meitnerium. Due to its presence in Group 11 it is a transition metal and so probably metallic and solid.

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".

External links

• WebElements.com - Roentgenium (http://www.webelements.com/webelements/elements/text/Rg/index.html)
• IUPAC: Proposal of name roentgenium for element 111 (http://www.iupac.org/reports/provisional/abstract04/corish_311004.html)
• IUPAC: Element 111 is named roentgenium (http://www.iupac.org/news/archives/2004/naming111.html)
• Apsidium - Roentgenium Element 111 (http://www.apsidium.com/elements/111.htm)

ca:unununi de:Roentgenium et:Element 111 es:Unununio fr:Unununium it:Roentgenio nl:Unununium ja:ウンウンウニウム pl:Roentgen (pierwiastek) sv:Unununium zh:Uuu