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Roentgenium

Darmstadtium – Unununium – Ununbium Au Uuu         Full table
Known properties
Name, Symbol, Number	unununium, Uuu, 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

Unununium (proposed name: Roentgenium) is a chemical element in the periodic table that has the symbol 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 Uuu-272), by the fusion of bismuth-209 and nickel-64 in a linear accelerator. (Nickel was bombarded onto the target.)

Unununium is a temporary IUPAC systematic element name. The name roentgenium has been proposed as a permanent name.