can be extracted by reduction of the
oxide using magnesium (*Kroll
process) or aluminium (*Goldschmidt process). Often the ore is
mixed with iron ore and reduced in
an electric furnace to produce ferromanganese for use in alloy steels.
The element is fairly electropositive;
it combines with oxygen, nitrogen,
and other nonmetals when heated
(but not with hydrogen). Salts of
manganese contain the element in
the +2 and +3 oxidation states. Manganese(II) salts are the more stable. It
also forms compounds in higher oxidation states, such as manganese(IV)
oxide and manganate(VI) and manganate(VII) salts. The element was
discovered in 1774 by Karl *Scheele.
A
• Information from the WebElements site
manganese(IV) oxide (manganese
dioxide) A black oxide made by heating manganese(II) nitrate. The compound also occurs naturally as
pyrolusite. It is a strong oxidizing
agent, used as a depolarizing agent in
voltaic cells.
manganic compounds Compounds of manganese in its +3 oxidation state; e.g. manganic oxide is
manganese(III) oxide, Mn 2 O 3 .
manganin A copper alloy containing 13–18% of manganese and 1–4%
of nickel. It has a high electrical resistance, which is relatively insensitive to temperature changes. It is
therefore suitable for use in resistance wire.
manganous compounds Compounds of manganese in its +2 oxidation state; e.g. manganous oxide is
manganese(II) oxide, MnO.
mannan See mannose.
Mannich reaction A reaction in
which a primary or secondary amine
reacts with methanal (formaldehyde)
and a carbonyl compound to produce
an amino-carbonyl compound. It
takes place in two stages. First the
amine reacts with methanol to form
a Schiff base:
R 2 N + H 2 CO → R 2 N
+ =CH 2 .
This then reacts with the carbonyl
compound:
R 2 N
+ =CH 2 + R
1 R
2 CHCOR
3
→
R 2 N–CH 2 –C(R
1 R
2 )COR
3 .
The reaction was Ürst reported by
Carl Mannich in 1912.
mannitol A polyhydric alcohol,
CH 2 OH(CHOH) 4 CH 2 OH, derived from
mannose or fructose. It is the main
soluble sugar in fungi and an important carbohydrate reserve in brown
algae. Mannitol is used as a sweetener in certain foodstuffs and as a diuretic to relieve Ûuid retention.
mannose A *monosaccharide,
C 6 H 12 O 6 , stereoisomeric with glucose, that occurs naturally only in
polymerized forms called mannans.
These are found in plants, fungi, and
bacteria, serving as food energy
stores.
manometer A device for measuring pressure differences, usually by
the difference in height of two liquid
columns. The simplest type is the Utube manometer, which consists of a
glass tube bent into the shape of a U.
If a pressure to be measured is fed to
one side of the U-tube and the other
is open to the atmosphere, the difference in level of the liquid in the two
limbs gives a measure of the unknown pressure.
many-body problem The problem that it is very difÜcult to obtain
exact solutions to systems involving
interactions between more than two
bodies – using either classical mechanics or quantum mechanics. To
understand the physics of many-body
systems it is necessary to make use of
341
many-body problem
m
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oxide using magnesium (*Kroll
process) or aluminium (*Goldschmidt process). Often the ore is
mixed with iron ore and reduced in
an electric furnace to produce ferromanganese for use in alloy steels.
The element is fairly electropositive;
it combines with oxygen, nitrogen,
and other nonmetals when heated
(but not with hydrogen). Salts of
manganese contain the element in
the +2 and +3 oxidation states. Manganese(II) salts are the more stable. It
also forms compounds in higher oxidation states, such as manganese(IV)
oxide and manganate(VI) and manganate(VII) salts. The element was
discovered in 1774 by Karl *Scheele.
A
• Information from the WebElements site
manganese(IV) oxide (manganese
dioxide) A black oxide made by heating manganese(II) nitrate. The compound also occurs naturally as
pyrolusite. It is a strong oxidizing
agent, used as a depolarizing agent in
voltaic cells.
manganic compounds Compounds of manganese in its +3 oxidation state; e.g. manganic oxide is
manganese(III) oxide, Mn 2 O 3 .
manganin A copper alloy containing 13–18% of manganese and 1–4%
of nickel. It has a high electrical resistance, which is relatively insensitive to temperature changes. It is
therefore suitable for use in resistance wire.
manganous compounds Compounds of manganese in its +2 oxidation state; e.g. manganous oxide is
manganese(II) oxide, MnO.
mannan See mannose.
Mannich reaction A reaction in
which a primary or secondary amine
reacts with methanal (formaldehyde)
and a carbonyl compound to produce
an amino-carbonyl compound. It
takes place in two stages. First the
amine reacts with methanol to form
a Schiff base:
R 2 N + H 2 CO → R 2 N
+ =CH 2 .
This then reacts with the carbonyl
compound:
R 2 N
+ =CH 2 + R
1 R
2 CHCOR
3
→
R 2 N–CH 2 –C(R
1 R
2 )COR
3 .
The reaction was Ürst reported by
Carl Mannich in 1912.
mannitol A polyhydric alcohol,
CH 2 OH(CHOH) 4 CH 2 OH, derived from
mannose or fructose. It is the main
soluble sugar in fungi and an important carbohydrate reserve in brown
algae. Mannitol is used as a sweetener in certain foodstuffs and as a diuretic to relieve Ûuid retention.
mannose A *monosaccharide,
C 6 H 12 O 6 , stereoisomeric with glucose, that occurs naturally only in
polymerized forms called mannans.
These are found in plants, fungi, and
bacteria, serving as food energy
stores.
manometer A device for measuring pressure differences, usually by
the difference in height of two liquid
columns. The simplest type is the Utube manometer, which consists of a
glass tube bent into the shape of a U.
If a pressure to be measured is fed to
one side of the U-tube and the other
is open to the atmosphere, the difference in level of the liquid in the two
limbs gives a measure of the unknown pressure.
many-body problem The problem that it is very difÜcult to obtain
exact solutions to systems involving
interactions between more than two
bodies – using either classical mechanics or quantum mechanics. To
understand the physics of many-body
systems it is necessary to make use of
341
many-body problem
m
www.AzShimi.ir www.AzShimi.com