Periodic Table of Elements




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 (Gesellschaft für Schwerionenforschung) in Darmstadt.

Name: Meitnerium
Symbol: Mt
Atomic number: 109
Atomic weight: 276.15
State: solid presumably
Group, period, block: 9, 7, d
Color: unknown
Classification: unknown but probably a transition metal
Electron configuration: 5f14 6d7 7s2

Physical properties

Density: 37.4 g/cm-3
Melting point: no data
Boiling point: no data

Atomic properties

Oxidation states: 8, 6, 4, 3, 1
Electronegativity: no data
Ionization energies: 1st: 800.8 kJ·mol-1
Covalent radius: 129 pm
Van der Waals radius: no data
  • Mt
  • Electron Configuration


Meitnerium is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 266Mt in 1982. There are seven known isotopes, from 266Mt to 278Mt. The longest-lived of the known isotopes is 278Mt with a half-life of 8 seconds.