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Roentgenium is a chemical element in the periodic table that has the symbol Rg and atomic number 111. It is a synthetic element whose longest-lived isotope has a mass of 280 and a half-life of 3.6 seconds.


Name, Symbol, Number roentgenium, Rg, 111
Chemical series transition metals
Group, Period, Block 11, 7, d
Appearance unknown, predicted colourless
Standard atomic weight [280]g·mol-1
Electrons per shell 2, 8, 18, 32, 32, 17, 2
Phase presumably a solid
CAS registry number 54386-24-2


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