manganese-dioxide

manganese

[mang-guh-nees, -neez]
noun Chemistry.
a hard, brittle, grayish-white, metallic element, an oxide of which, MnO 2 (manganese dioxide) is a valuable oxidizing agent: used chiefly as an alloying agent in steel to give it toughness. Symbol: Mn; atomic weight: 54.938; atomic number: 25; specific gravity: 7.2 at 20°C.

Origin:
1670–80; < French manganèse < Italian manganese, alteration of Medieval Latin magnesia magnesia

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World English Dictionary
manganese (ˈmæŋɡəˌniːz)
 
n
a brittle greyish-white metallic element that exists in four allotropic forms, occurring principally in pyrolusite and rhodonite: used in making steel and ferromagnetic alloys. Symbol: Mn; atomic no: 25; atomic wt: 54.93805; valency: 1, 2, 3, 4, 6, or 7; relative density: 7.21--7.44; melting pt: 1246±3°C; boiling pt: 2062°C
 
[C17: via French from Italian manganese, probably altered form of Medieval Latin magnesia]

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Etymonline
Word Origin & History

manganese
1676, from Fr. manganèse (16c.), from It. manganese, alt. of M.L. magnesia (see magnesia).
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

manganese man·ga·nese (māng'gə-nēz', -nēs')
n.
Symbol Mn
A brittle metallic element, having several allotropes. It is alloyed with steel to increase strength. Atomic number 25; atomic weight 54.9380; melting point 1,246°C; boiling point 2,061°C; specific gravity 7.21 to 7.44; valence 1, 2, 3, 4, 6, 7.

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Science Dictionary
manganese   (māng'gə-nēz')  Pronunciation Key 
Symbol Mn
A grayish-white, hard, brittle metallic element that occurs in several different minerals and in nodules on the ocean floor. It is used to increase the hardness and strength of steel and other important alloys. Atomic number 25; atomic weight 54.9380; melting point 1,244°C; boiling point 1,962°C; specific gravity 7.21 to 7.44; valence 1, 2, 3, 4, 6, 7. See Periodic Table.
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