Manganese

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Manganese

This is manganese.

Symbol Mn
Atomic number 25
Atomic mass 54.9380 amu

Manganese was first isolated in 1774 when the mineral pyrolusite, MnO2, was fired in a charcoal container. When the oven cooled, a small amount of greyish manganese was produced.

Distinguishing properties

Elemental manganese is hard and shiny. Like vanadium and chromium, it is used mostly to make steel alloys. A small amount of manganese (< 1%) makes steel easier to roll, forge, and weld. It also increases the resistance of steel to impact. The steel used in railroad tracks contain as much as 1.2 % manganese. Steel made with 12% manganese is tough enough to be used for naval armour and bulldozer blades. Small amounts of manganese are addded to aluminum beverage cans and bronze alloys to make them stiffer and tougher.

Manganese exhibits many oxidation states. All manganese species with oxidation states greater than +2 act as oxidizing agents. The purple permanganate ion, MnO4- ion is particularly powerful.

Occurrence

Manganese ore was first confused with magnetic iron ore. The most common oxide and mineral is pyrolusite. Mines in the Soviet Union, India, and South Africa produce ores containing as much as 40% manganese. Another promising source of manganese is the "nodules" that are scattered over large portions of the ocean floor. These chunks which vary from a few millimeters to a few meters in diameter, consist mainly of manganes and iron oxides. Billions of tons are present, but mining them presents major technical and political challenges. Cooperation will be required to mine the nodules such that the rewards will be shared globally.

Usage

Uses of manganese include:

  • manganese (IV) oxide, MnO2, in dry-cell and alkaline batteries,
  • permanganic acid, HMnO4, which is as strong as perchloric acid.
  • its biological role to activate many enzymes. It is crucial to the effectiveness of vitamin B1. Without manganese, bones grow spongier and break more easily.

See also

Periodic table of the elements