Hassium - Meitnerium - Darmstadtium

Full table
Known properties
Name, Symbol, NumberMeitnerium, 109, Mt
Chemical series Transition metals
Group, Period, Block9, 7 , d
Appearance unknown; probably metallic,
silvery white or gray
Atomic weight [268] amu
Electron configuration probably [Rn] 5f14 6d7 7s2
e- 's per energy level2, 8, 18, 32, 32, 15, 2
State of matter Presumably a solid

Meitnerium is a chemical element in the periodic table that has the symbol Mt and atomic number 109. It is a synthetic element whose most stable isotope is Mt-266 with a half-life of 3.4 ms.


Meitnerium was first synthesized on August 29, 1982 by a German research team led by Peter Armbruster and Gottfried Münzenberg at the Institute for Heavy Ion Research at Darmstadt.
The team did this by bombing a target of bismuth-209 with accelerated nuclei of iron-58. The creation of this element demonstrated that nuclear fusion techniques could be used to make new, heavy nuclei.

The name meitnerium was suggested in honor of the Austrian-Swedish physicist and mathematician Lise Meitner, but there was an element naming controversy as to what the elements from 101 to 109 were to be called; thus IUPAC adopted unnilennium (symbol Une) as a temporary, systematic element name. However in 1997 they resolved the dispute and adopted the current name.

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