Roentgenium: the essentials
Roentgenium, was discovered on 8th December 1994 at the GSI in Darmstadt, Germany. Further information on element 111 is here (outside WebElements). The information following is an abstract of this source. The interested reader should consult the on-line version of The Wonderful World of Atoms and Nuclei 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).
Roentgenium: historical information
Element 111, roentgenium, was discovered towards the end of 1994 at the GSI in Darmstadt, Germany. Three atoms of an isotope 272Uuu were produced in reactions between 209Bi targets and 64Ni projectiles. To achieve this, the nickel atoms were accelerated to high energies by the heavy ion accelerator UNILAC at GSI and directed onto a lead target.
Roentgenium: physical properties
Roentgenium: orbital properties
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.