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manganese (Mn)





manganese
A gray-white or silvery, brittle metallic element in group VIIB of the periodic table; a transition element. It was first isolated in 1774.

Manganese is found naturally in the ores pyrolusite, manganite, and hausmannite, and manganese nodule. It occurs in several allotropic forms. Elementary manganese is obtained by the reduction of manganese (IV) oxide with aluminum in a furnace, or by electrolysis. When smelted with iron ore, manganese ore gives the alloys spiegeleisen and ferromanganese, widely used in steel production to increase hardness, resistance, and other properties. Manganese also forms useful alloys with some nonferrous metals.

Manganese is fairly reactive, resembling iron chemically. Its main oxidation states are +2, +3, +4, +6, and +7. The most common isotope is 55Mn (100%).


atomic number 25
relative atomic mass 54.938
relative density 7.21–7.44
melting point 1,246°C (2,275°F)
boiling point 2,061°C (3,742°F)


Manganese compounds

Manganese forms two series of salts, termed manganese(II), or manganous, and manganese(III), or manganic. It also forms manganate(VI), containing the ion MnO42-, and manganate(VII) (permanganate) MnO4-.

Manganese (IV) oxide (MnO2), a black crystalline solid, is widely used as an oxidizing agent and as a depolarizer in electric dry cells. Permanganate (MnO4-) is used in nickel refining and tanning, and as a bleach, disinfectant, and powerful oxidizing agent. Manganese (II) sulfate (MnSO4) is a component of some fertilizers.


Manganese and health

Inhaled my miners in underventilated mines, manganese oxide causes brain damage and symptoms very similar to those of parkinsonism. Minute quantities of manganese are needed by the body. See trace element.


Related category

   • INORGANIC CHEMISTRY