unnilennium

Temporary name of the chemical element with atomic number 109. It was first synthesized (one atom!) and identified in 1982 by P. Armbruster, G. Münzenberg and colleagues at the Gesellshaft für Schwerionenforschung at Darmstadt, Germany¹. The name meitnerium (symbol, Mt) was proposed, honoring the physicist Lise Meitner, co-discoverer of nuclear fission, and accepted in 1997 by the IUPAC's Commission on Nomenclature of Inorganic Chemistry.²

1.
P. Armbruster.
Proceedings of the International Conference on Nuclear Physics, pages 343–363, Florence, 1983.

G. Münzenberg et al.
Evidence for element 109 from one correlated decay sequence following the fusion of 58Fe with 209Bi.
Zeitung Phys A315, pages 145–158 (1984).

2.
Inorganic Chemistry Division; Commission on Nomenclature of Inorganic Chemistry.
Names and Symbols of Transfermium Elements (IUPAC recommendation 1997)
Pure and Applied Chemistry, vol. 69, no. 12, pages 2471-2473 (1997).

Available on the Web as a pdf file accessible through www.iupac.org/projects/1995/220_30_95.html