Meitnerium (Mt)

Meitnerium is a radioactive chemical element with the atomic number 109 in the periodic table. Since it’s synthetically produced, meitnerium cannot be found in Earth’s crust. Being a member of the transition metals family of the periodic table, the element 109 is assumed to be the heaviest metal of group 9, after iridium, rhodium, and cobalt

Chemical and Physical Properties of Meitnerium

Symbol of MietneriumMt
Atomic Number of Mietnerium109
Atomic Mass of Mietnerium-266.1378
Uses of MietneriumIt has no significant commercial applications.
Description of MietneriumSynthetic radioactive metal.
Melting Point of MietneriumUnknown
Boiling Point of MietneriumUnknown
Group of MietneriumTransition Metal
Shells of Mietnerium2,8,18,32,32,15,2
Orbitals of Mietnerium[Rn] 5f14 6d7 7s2
Valence of Mietnerium
Crystal Structure of MietneriumUnknown
Electro Negativity of Mietnerium
Covalent Radius of Mietnerium
Atomic Radius of Mietnerium
Atomic Volume of Mietnerium
Name Origin of MietneriumNamed in honor of Lise Mietner
Discovered of Mietnerium ByHeavy Ion Research Laboratory (HIRL)
Pronounced of MietneriumMITE-ner-i-um
Oxydation States of Mietnerium
Density of Mietnerium
Group number9
Period7 (d-block)
Physical stateA solid, radioactive metal at room temperature
Half-lifeFrom 1.2(4) milliseconds to 67 seconds
Electronegativity according to PaulingUnknown
Most characteristic isotope266Mt
Discovery dateIn 1982 by Peter Armbruster, Gottfried Münzenberg (also: Gottfried Munzenberg, Gottfried Münzenber) and colleagues


With the periodic table symbol Mt, atomic number 109, atomic mass of [278]g.mol-1, and electron configuration [Rn] 5f146d77s2, meitnerium is one of the least studied chemical elements due to its relatively recent synthesization and high radioactivity. For this reason, its chemical properties are assumed by the properties of the group 9 elements of the periodic table.

This group is made up of the elements meitnerium, iridium, rhodium, and cobalt. All of these chemicals are also classified as d-block transition elements. Meitnerium is expected to share chemical properties with iridium, cobalt, and rhodium.         

Furthermore, this synthetically produced element has a face-centered cubic structure. The meitnerium’s atomic structure consists of 109 protons and 109 electrons, and its shell structure is Its atomic radius is assumed to be around 128 pm.

How Was Meitnerium Discovered?

The first atoms of meitnerium were synthesized by a team of scientists employed at the Gesellschaft für Schwerionenforschung (The Institute for Heavy Ion Research) in Darmstadt, Germany. In 1982, the team led by the German physicists Peter Armbruster (1930) and Gottfried Münzenberg (1940) attempted bombardment of a bismuth-209 target with iron-58 nuclei in a linear accelerator. 

By using a parent-daughter correlation technique, the GSI team at the Heavy Ion Research Laboratory succeeded in identifying a single atom of meitnerium-266. In 1985, Mt alpha decays from californium-246 (246Cf) were detected, which only confirmed meitnerium as a new discovery in the world of science. 

With this, the German team of scientists not only succeeded in synthesizing the first meitnerium atom of the new element but also in conducting the first successful demonstration of the use of fusion for the purpose of making new, heavy nuclei by combining atoms of two lighter elements. 

How Did Meitnerium Get Its Name?

Originally predicted as the element unnilennium, element 109 got its name in honor of the Austrian physicist Lise Meitner. In September 1992, the German team of scientists (the GSI team) who worked on the synthetization of the first meitnerium atoms proposed the name meitnerium (Mt). This proposition was accepted by IUPAC (International Union of Pure and Applied Chemistry) in 1997, thus immortalizing Meitner’s contributions to the world of chemistry and science. 

Lise Meitner (1878 – 1968)

The Austrian-Swedish physicist Lise Meitner was born in 1878, in Vienna – then the capital of the Austro-Hungarian Empire. Being academically inclined since the early childhood days, Meitner was encouraged to think independently by her noble parents. 

Having a great interest in physics and especially radioactivity, Lise Meitner received her Ph.D. in physics in December 1905, passing the exam with the highest honors. After years of work together with the pioneer in the fields of radioactivity and radiochemistry, the German chemist Otto Hahn, they came to the discovery of the radioactive recoil, a purely quantum phenomenon. Meitner and Hahn provided scientific evidence that this phenomenon can be used for the production of elements with very high purity.

Meitner’s Discovery of Nuclear Fission

By bombarding uranium (element 92) with neutrons, the Italian physicist and the creator of the world’s first nuclear reactor Enrico Fermi opened the doors of nuclear physics to the concept of nuclear fission and the production of transuranic elements. This concept highly intrigued Meitner who suggested her colleague Hahn to test Fermi’s method. Their chemical trials on the process of creating transuranic elements resulted in numerous published research papers. 

In an effort to produce transuranium elements herself, Meitner observed that by splitting the atomic nucleus of uranium, massive energy is being released in a form of an enormous explosion. She also projected that the uranium nucleus after neutron capture would be divided into two nuclei of approximately equal size, while the released energy from the difference in stability between uranium and elements around barium was estimated to be around 200 million electron volts. 

This new type of nuclear reaction that was labeled as nuclear fission later led to the discovery of nuclear reactors used for the generation of heat and electricity. The great discovery of Meitner also led to the production of nuclear weapons, an achievement of which she was not proud of. 

Where Can You Find Meitnerium?

Meitnerium is a highly radioactive chemical element that has been synthesized in extremely small quantities by cold fusion reactions. It’s made only in a highly controlled laboratory environment by bombarding atoms of bismuth-209 (209Bi) with ions of iron-58 (58Fe) using a linear accelerator. Furthermore, the isotopes of element 109 have a very short life, which is also one of the reasons why this chemical does not exist in nature in any of its forms. 

Meitnerium in Everyday Life

This highly radioactive chemical element has not known any practical application. In addition, since no sufficiently stable isotopes of meitnerium were produced, no chemical experiments have also been conducted on element 109. 

How Dangerous Is Meitnerium?

Considering the strong radioactive emissions, meitnerium could be considered extremely dangerous provided there are visible quantities of the chemical produced. However, due to the very unstable nature, the meitnerium isotopes quickly decompose and would not have any adverse effects on human health. 

Environmental Effects of Meitnerium

Due to the extremely short life of the meitnerium isotopes, the effects of this chemical element on the environment cannot be considered. 

Isotopes of Meitnerium

There are nine highly radioactive meitnerium isotopes with mass numbers ranging from 266Mt to 282Mt. Among them, meitnerium-266 is the only form of the element 107 that has been directly synthesized. All of the other meitnerium isotopes are decay products of the heavier elements, such as bohrium (Bh). None of the isotopes of meitnerium are stable by nature. 

Having a half-life of 8 seconds, the meitnerium-278 isotope is believed to be the longest-lived form of this radioactive element. It decays into bohrium-274 (274Bh) through alpha decay. However, the ongoing studies on this element could prove the 282Mt isotope as the meitnerium form with the longest life of 67 seconds. This fact is yet to be confirmed by scientists. 



[n 1]

ZNIsotopic mass (Da)


[n 2][n 3]







Spin and



[n 4][n 5]

Excitation energy
266Mt109157266.13737(33)#1.2(4) msα262Bh 
268Mt[n 6]109159268.13865(25)#21(+8−5) msα264Bh5+#, 6+#
268mMt[n 7]0+X keV0.07(+10−3) sα264Bh 
270Mt[n 8]109161270.14033(18)#570 msα266Bh 
270mMt[n 7] 1.1 s?α266Bh 
274Mt[n 9]109165274.14725(38)#450 msα270Bh 
275Mt[n 10]109166275.14882(50)#9.7(+460−44) msα271Bh 
276Mt[n 11]109167276.15159(59)#0.72(+87-25) sα272Bh 
277Mt[n 12]109168277.15327(82)#~5 ms[2][3]SF(various) 
278Mt[n 13]109169278.15631(68)#7.6 s[4]α274Bh 
282Mt[n 14]109173 67 s?α278Bh 

Source: Wikipedia

List of Meitnerium Compounds 

Owing to the fact that this radioactive synthetic element has been produced in minuscule quantities,  no compounds have been made with it yet. The most commonly adopted oxidation states of meitnerium are predicted to be the +6, +3, and +1. 

5 Interesting Facts and Explanations

  1. Meitnerium is one of the few chemical elements of the periodic table that has been named without any controversy or dispute on the subject of its name or the discovery.
  2. Being aware of the hazardous effects of radioactivity, Lise Meitner was among the rare scientists of the time who was taking all measures of precaution in her working environment against radioactivity. 
  3. During World War I, Meitner was helping the soldiers at the front line by performing x-ray imaging tests.
  4. Lise Meitner was invited to collaborate on the Manhattan project, but she refused the offer because she didn’t want her work to contribute to making a bomb with devastating effects upon people and the environment. 
  5. The German team of scientists who synthesized meitnerium also discovered the elements hassium (Hs) and bohrium (Bh).