Meitnerium

Meitnerium (symbol: Mt) is a chemical element with atomic number 109. It is a synthetic element—meaning it does not occur naturally but is produced in equipment called an accelerator, which collides atoms at high speed. All known isotopes are radioactive and decay rapidly.

Because the quantity produced is extremely small—only a few atoms at a time—its chemical properties cannot be directly confirmed. Most predictions about it are based on its position in the periodic table.

Position in the periodic table

Meitnerium is located in period 7 of the periodic table, group 9, in the same row as cobalt, rhodium, and iridium. It is classified as one of the transactinide elements—those with atomic number greater than 103. The prediction that it resembles iridium has not yet been confirmed experimentally.

Discovery and naming

The element was first synthesized in 1982 at the GSI research center in Darmstadt, Germany, by a team led by Peter Armbruster and Gottfried Münzenberg. The method used was bombardment of bismuth with ions of iron, followed by observation of the alpha decay chain produced.

It was named after physicist Lise Meitner, one of the scientists who explained nuclear fission. The name was officially adopted in 1997 when IUPAC (the International Union of Pure and Applied Chemistry) decided on the names of the heavy elements.

Isotopes and stability

Several isotopes of Mt are known, differing in their number of neutrons. Their half-lives range from fractions of a second to several seconds, with heavier isotopes generally being more stable than lighter ones. The dominant decay mode is alpha decay.

Applications

Meitnerium has no commercial or industrial applications. It is used only in scientific research concerning nuclear structure and the limits of atomic stability.