- Meitnerium (Mt) is a synthetic, highly radioactive element with atomic number 109, belonging to Group 9 of the periodic table, directly beneath iridium.
- It is classified as a transactinide and part of the 6d transition series. Its predicted electron configuration is [Rn] 5f¹⁴ 6d⁷ 7s², consistent with its position in Group 9, though relativistic effects may alter the distribution slightly.
- Meitnerium is expected to display a predominant oxidation state of +3, similar to cobalt, rhodium, and iridium, with possible higher states such as +6. Its atomic structure contains one hundred and nine protons, around one hundred and sixty-nine to one hundred and seventy-two neutrons depending on the isotope, and one hundred and nine electrons arranged in seven shells.
- The most stable known isotope is meitnerium-278 (²⁷⁸Mt), which has a half-life of about 7.6 seconds. Other isotopes typically decay within milliseconds to a few seconds.
- Meitnerium was first synthesized on August 29, 1982, by a research team led by Peter Armbruster and Gottfried Münzenberg at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany. The team bombarded a bismuth-209 (²⁰⁹Bi) target with accelerated iron-58 (⁵⁸Fe) ions, resulting in the production of meitnerium-266 (²⁶⁶Mt). Only a single atom was detected, but its decay pattern provided confirmation of the new element’s existence. This made meitnerium the first element discovered by colliding two nuclei of relatively heavy elements (bismuth and iron).
- The element was named meitnerium in honor of Austrian-Swedish physicist Lise Meitner, who played a crucial role in the discovery of nuclear fission alongside Otto Hahn and Fritz Strassmann. Despite her major contributions, Meitner was overlooked for the 1944 Nobel Prize in Chemistry, which was awarded solely to Hahn. Naming element 109 after her served as a recognition of her scientific legacy. The symbol Mt was officially approved by IUPAC in 1997.
- Due to its extremely short half-life and the fact that it is produced only atom by atom, meitnerium has no practical applications outside of basic research. Its main value lies in expanding knowledge of the periodic table and testing chemical periodicity in the transactinide region.
- Chemically, meitnerium is predicted to behave like iridium, forming stable +3 compounds and possibly exhibiting higher oxidation states in oxides or halides. However, experimental chemical studies have not yet been performed due to the tiny number of atoms produced and their rapid decay.
- Biologically, meitnerium has no role and is considered highly radiotoxic, though its short existence means it poses no biological danger outside nuclear laboratories.
- Environmentally, meitnerium does not occur naturally and is produced only under highly controlled conditions in particle accelerators. Its fleeting half-lives ensure that it leaves no lasting environmental impact.
