Manganese Information
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Manganese Element
Manganese is a chemical element
with the symbol Mn and atomic number 25. It is found as a free element in
nature; it is often found in minerals in combination with iron. Manganese is a
transition metal with a multifaceted array of industrial alloy uses,
particularly in stainless steels.
Historically, manganese is
named for pyrolusite and other black minerals from the region of Magnesia in
Greece, which also gave its name to magnesium and the iron ore magnetite. By
the mid-18th century, Swedish-German chemist Carl Wilhelm Scheele had used
pyrolusite to produce chlorine. Scheele and others were aware that pyrolusite
(now known to be manganese dioxide) contained a new element, but they were
unable to isolate it. Johan Gottlieb Gahn was the first to isolate an impure
sample of manganese metal in 1774, which he did by reducing the dioxide with
carbon.
Manganese combined with other
elements is widely distributed in Earth’s crust. Manganese is second only to
iron among the transition elements in its abundance in Earth’s crust; it is
roughly similar to iron in its physical and chemical properties but is harder
and more brittle. It occurs in a number of substantial deposits, of which the
most important ores (which are mainly oxides) consist primarily of manganese
dioxide (MnO2) in the form of pyrolusite, romanechite, and wad. Manganese is
essential to plant growth and is involved in the assimilation of nitrates in
green plants and algae. It is an essential trace element in higher animals, in
which it participates in the action of many enzymes. Lack of manganese causes
testicular atrophy. An excess of this element in plants and animals is toxic.
Manganese phosphating is used
for rust and corrosion prevention on steel. Ionized manganese is used
industrially as pigments of various colors, which depend on the oxidation state
of the ions. The permanganates of alkali and alkaline earth metals are powerful
oxidizers. Manganese dioxide is used as the cathode (electron acceptor)
material in zinc-carbon and alkaline batteries.
In biology, manganese(II) ions
function as cofactors for a large variety of enzymes with many functions.[3]
Manganese enzymes are particularly essential in detoxification of superoxide
free radicals in organisms that must deal with elemental oxygen. Manganese also
functions in the oxygen-evolving complex of photosynthetic plants. While the
element is a required trace mineral for all known living organisms, it also
acts as a neurotoxin in larger amounts. Especially through inhalation, it can
cause manganism, a condition in mammals leading to neurological damage that is
sometimes irreversible.
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