from Wikipedia, the free encyclopedia
Name , symbol , atomic number Meitnerium, Mt, 109
Element category
Group , period , block 9 , 7 , d
CAS number 54038-01-6
Atomic mass 268 u
Electron configuration [ Rn ] 5 f 14 6 d 7 7 s 2
1. Ionization energy 801 kJ / mol
isotope NH t 1/2 ZA ZE (M eV ) ZP
For other isotopes see list of isotopes
Hazard and safety information
GHS hazard labeling
no classification available
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions .

Meitnerium (formerly: " Eka -Iridium") is an artificial chemical element with the element symbol Mt and the atomic number 109. It is one of the transactinoids and is in the 9th  IUPAC group in the periodic table of the elements and thus to the cobalt group . It was named in honor of the Austrian-Swedish physicist Lise Meitner .


Meitnerium was first produced in 1982 (and then again in February 1988) at the Society for Heavy Ion Research in Darmstadt by bombarding bismuth with iron . It was initially called Unnilennium (symbol Une), since 1997 the current name.


Meitnerium is an extremely short-lived radioactive metal . So far, seven isotopes (here radionuclides ) have been generated. The longest-lived isotope is 276 Mt, the half-life of which is 720 milliseconds. Because of this very rapid decay , little is known about the other properties of the element. Nevertheless, it is assumed that meitnerium is largely colored silver-gray. Meitnerium occurs only in synthesized form.

safety instructions

There is no classification according to the CLP regulation or other regulations because only a few atoms of this element can be produced at the same time and thus far too few for a chemical or physical hazard.

Web links

Commons : Meitnerium  - collection of images, videos and audio files
Wiktionary: Meitnerium  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Entry on meitnerium at WebElements, , accessed on June 13, 2020.
  2. The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling. With regard to other hazards, this element has either not yet been classified or a reliable and citable source has not yet been found.
  3. ^ Names and Symbols of Transfermium Elements (IUPAC Recommendations 1997). (PDF; 167 kB).
  4. Meitnerium (Mt) - Periodic Table of the Elements (PSE). Retrieved July 27, 2018 .