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Definition: meitnerium from The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide

Synthesized radioactive element of the transactinide series, atomic number 109, relative atomic mass 266. It was first produced in 1982 at the Laboratory for Heavy-Ion Research in Darmstadt, Germany, by fusing bismuth and iron nuclei; it took a week to obtain a single new, fused nucleus. It was known by the temporary name unnilennium until 1997 when it was named after the Austrian-born Swedish physicist Lise Meitner.

Summary Article: meitnerium
from The Columbia Encyclopedia

(mītnĭr'ēӘm), artificially produced radioactive chemical element; symbol Mt; at. no. 109; mass number of most stable isotope 276; m.p., b.p., sp. gr., and valence unknown. Situated in Group 9 of the periodic table it is expected to have properties similar to those of iridium.

In 1982 a German research team led by P. Armbruster and G. Münzenberg at the Institute for Heavy Ion Research at Darmstadt bombarded bismuth-209 atoms with iron-58 ions. On the tenth day of the experiment, one atom was unambiguously identified as an isotope of element 109 with mass number 266 and a half-life of 3.4 msec. The Germans suggested the name meitnerium to honor the Austrian-Swedish physicist and mathematician Lise Meitner. This name was recognized internationally in 1997. The most stable isotope of meitnerium, meitnerium-276, has a half-life of 0.72 sec.

See also synthetic elements; transuranium elements.

The Columbia Encyclopedia, © Columbia University Press 2018

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