manganese (Mn)
A gray-white or silvery, brittle metallic element
in group VIIB of the periodic table;
a transition element. It is found
naturally in the ores pyrolusite and
manganite, and 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.
| 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 (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
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