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Roentgenium - Definition and Overview |
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| Known properties
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| Name, Symbol, Number | roentgenium, Rg, 111
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| Chemical series | Transition metals
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| Group, Period, Block | 11, 7 , d
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| Appearance | unknown; probably metallic,
silvery white or gray
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| Atomic weight | [272] amu
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| Electron configuration | probably [Rn]5f14 6d10 7s1
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| e- 's per energy level | 2, 8, 18, 32, 32, 17, 2
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| State of matter | Presumably a solid
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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. 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".
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