Chemical Element: meitnerium

(Latin: named for Lise Meitner, an Austrian physicist; radioactive metal)

Chemical-Element Information

Symbol: Mt
Atomic number: 109
Year discovered: 1982

Discovered by: Peter Armbruster, Gottfried Münzenber, and their co-workers at Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany.


  • Lise Meitner (1878-1968) was a distinguished Austrian physicist, whose main personal achievement (among many others) was the explanation of the relation between beta and gamma rays.
  • She was born in Vienna on November 7, 1878, the third of eight children of a Viennese lawyer.
  • After receiving her doctorate, in 1906, she went to Berlin, in 1907, and joined the chemist Otto Hahn in research on radioactivity; she also studied under Max Planck and for a time was his assistant.
  • During their three decades of joint work, she and Hahn discovered protactinium and several other radioactive substances.
  • Lise Meitner, with her nephew Otto R. Frisch, after clarifying the physical characteristics of the division of a heavy atomic nucleus, proposed, early in 1939, the name “fission” for the process.
  • In August, 1982, the first atom of the element meitnerium with atomic number 109 was detected at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany.
  • The isotope of element 109, that was discovered, has an atomic mass number of 266 (that is, 266 times heavier than hydrogen).
  • The new element was produced by fusing an iron and a bismuth atom together in a reaction that produces a neutron.
  • This was achieved by accelerating the iron atoms to high energy in the heavy ion accelerator UNILAC at GSI.
  • Element meitnerium was formerly known as unnilennium (Une) which is the Latin equivalent for the number “109”.

Name in other languages:

French: meitnerium

German: Meitnerium

Italian: meitnerio

Spanish: meitnerio


Information about other elements may be seen at this Chemical Elements List.

A special unit about words that include chemo-, chem- may be seen here.