Roentgenium, was discovered on 8th December 1994 at the GSI in Darmstadt, Germany. The interested reader should consult the on-line version ofCreating Super Heavy Elements for a fascinating insight into research on "super-heavy" atoms.
Chemically, roentgenium should be in the same group as the elements copper, silver, and gold (Group 11).
Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of roentgenium where known.
Roentgenium wasdiscovered by S. Hofmann, V. Ninov, F. P. Hessberger, P. Armbruster, H. Folger, G. Münzenberg, and others in 1994 at Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany..Origin of name: the proposed name roentgenium has yet ot be accepted formally, but lies within the long established tradition of naming elements to honour famous scientists. Wilhelm Conrad Roentgen discovered X-rays in 1895.
Isolation: only a few atoms of element 111, roentgenium, have ever been made through a nuclear reaction involving fusion of an isotope of bismuth,209Bi, with one of nickel,64Ni.
209Bi +64Ni →272Rg +1n
Isolation of an observable quantity has never been achieved, and may well never be.
Density of solid: 24400 (predicted) kg m-3
Molar volume: 12 (rough estimate based upon density estimate) cm3
Thermal conductivity: (no data) W m‑1 K‑1
Melting point: (no data) K
Boiling point: (no data) K
Enthalpy of fusion: 20.5 kJ mol-1
Atomic radius (empirical): (no data) pm
Molecular single bond covalent radius: 121 (coordination number 2) ppm
van der Waals radius: (no data) ppm
Pauling electronegativity: (no data) (Pauling units)
Allred Rochow electronegativity: (no data) (Pauling units)
Mulliken-Jaffe electronegativity: (no data)
First ionisation energy: 1023 kJ mol‑1
Second ionisation energy: (no data) kJ mol‑1
Third ionisation energy: (no data) kJ mol‑1
Universe: (no data) ppb by weight
Crustal rocks: (no data) ppb by weight
Human: (no data) ppb by weight
