Roentgenium is a chemical element with symbol Rg and atomic number 111. It is an extremely radioactive synthetic element (an element that can be created in a laboratory but is not found in nature); the most stable known isotope, roentgenium-282, has a half-life of 2.1 minutes. Roentgenium was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany.
111
Atomic Number
282 u
Atomic Mass
null K
Melting Point
null K
Boiling Point
28.7 g/cm³
Density
null Å
Atomic Radius
null Å
Covalent Radius
null eV
First Ionization Energy
151
Electron Affinity
7
Number of Shells
2, 8, 18, 32, 32, 17, 2
Electron Shell Occupations