Meitnerium: Definition, Chemical Properties, Uses, Naming, Isotopes & Examples

Meitnerium (Mt) is an artificially produced element in the periodic table. It belongs to the transuranium group with 109 as its atomic number. Its chemical properties are predicted to be similar to that of iridium. Bismuth-209 targets were bombarded with beams of iron-58 ions for about ten days using a high energy linear accelerator by the GSI investigators under the supervision of Peter Armburster. The fusion reaction that resulted produced only one nucleus of the element. Half-life of the most stable isotope of the element, meitnerium-276, is 0.72 seconds.

Key Terms: Meitnerium, Transuranium, Iridium, Lise Meitner, Isotope, GSI, Half-life

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What is Meitnerium?

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Meitnerium is an artificial chemical element in the periodic table with atomic number 109 and symbol Mt. It was initially produced by a research team based in Germany at GSI Helmholtz Centre for Heavy Ion Research Laboratory under the supervision of Gottfried Munzenberg and Peter Armbruster in the year 1982. It belongs to the d-block and it is a transactinide element. A member of the 7th period, meitnerium is arranged in the 9th group of elements in the periodic table. Its properties are predicted to be similar to rhodium, iridium and cobalt which are lighter homologous elements.

As it is an artificially produced element, it does not have any natural or stable isotope. Laboratory productions of a number of radioactive isotopes have been successful, either by the decay of heavier metals or by the fusion of two atoms. These are always synthetically prepared as they cannot be found in a natural state on earth. Among its few isotopes, the one with the longest half-life is Meitnerium-278 with 4.5 seconds of half-life.

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Chemical Properties of Meitnerium

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Chemical properties of Meitnerium are as follows:

Its production is very limited and expensive due to its faster rate of decay. It belongs to the 6d series of transition metals. It is similar to iridium with respect to its atomic and ionic radii and ionization potentials. It is predicted to be a noble metal, similar to silver. The oxidation states of Meitnerium are most stable at the predicted values of +6, +1 and +3. In aqueous solutions, +3 is the most stable oxidation state. Tetrahalides of this element are also similar to iridium, explaining the predicted value of +4 as a possible oxidation state.

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History of Meitnerium

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A number of nuclei of Iron-58 were accelerated and made to hit on a target of Bismuth-209. The resultant product was a single nucleus of Meitnerium-266. The following equation shows a proper representation of this experiment.

²⁰⁹₈₃Bi + ⁵⁸₂₆Fe → ²⁶⁶₁₀₉Mt + n

The scientific community at the Joint Institute for Nuclear Research at Russia accepted this reaction and the product after three years.

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Naming of the Element

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According to the nomenclature procedure put forth by Mendeleev, the element was to be named as eka-iridium. Later, in 1979, the International Union for Pure and Applied Chemistry (IUPAC) introduced a set of uniform rules to name an element according to which this element was provided with a makeshift name of unnilennium. However, both these names were never commonly used by scientists. Element 109 or E109 or simply 109 were the names used by the scientific community to refer to this element.

It was in September 1992 that the team at GSI suggested naming the element as Meitnerium with the symbol Mt in honor of the Austrian physicist Lisa Meitner. Meitner was particularly revered in the scientific community for discovering protactinium along with Otto Hahn and was among the greatest exponents of nuclear fission. IUPAC accepted the name and it was made official in 1997.

In fact, Meitnerium and Curium are the only compounds named after real persons. Curium was named after Pierre and Marie Curie, the scientists.

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Isotopes of the Element

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There are no naturally occurring stable isotopes for meitnerium as it is a synthetically produced element. Many radioactive isotopes have been successfully synthesized in the laboratory. The fusion of two atoms or the decay of a heavier element or metal was used to produce them. There are eight different isotopes for meitnerium with atomic masses 266, 268, 270 and 274-278.

These are radioactive and unstable due to their synthetic nature. Compounds with greater atomic mass are more stable than the others.

The most stable isotope of meitnerium has the greater atomic mass of 278 and its half-life is 4.5 seconds. There is an unconfirmed isotope with atomic mass of 278 having a half-life of 67 seconds. All other isotopes of meitnerium have half-lives below one second.

The structure of meitnerium is cubic and crystal-like and it is similar to iridium. It is face-centered and solid at room temperature, if according to predictions. It is bound to be very heavy with a density of 37.4 gm/cm³. Thus, it becomes the second denser element in the periodic table, the first one being Hassium with a density of 41 gm/cm³. 

The Lanthanide and Actinide contractions present in the element along with its high atomic mass contribute to its relatively high density. Meitnerium is predicted to have paramagnetic properties as well. Its rate of decay is also relatively faster. Its covalent radius is estimated to be higher than that of iridium at a measure of 6-10 pm larger. Meitnerium has an atomic radius of almost 128 pm.

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Experimental Chemistry on Meitnerium

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There are only a few chemical compounds of meitnerium that are sufficiently volatile and they include Meitnerium Hexafluoride (MtF₆).

A stable scientific experiment requires a lot of atoms of the element in order to produce any tangible result. However, only ten atoms of meitnerium have been able to be produced at scale. Therefore, it is not sufficiently enough for experimentation even with the most stable isotope having a half life of 4.5 seconds.

An isotope of meitnerium, Meitnerium-270, was formed in the decay procedure of Nh-278 with a half-life of 0.69 seconds, which is comparatively sufficient for experimentation. Nevertheless, as a direct production procedure has not been formulated yet, it is difficult to be used for research purposes.

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Things to Remember

• Meitnerium is an artificially produced element with atomic number 109.
• Meitnerium chemical properties are predicted to be similar to that of iridium.
• Meitnerium is extremely radioactive in nature.
• The most stable isotope, Meitnerium-278, has the highest half-life of 4.5 seconds.

Also read: Ruthenium

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