metry it is a spherical top. If it has a
threefold or higher axis of symmetry
it is a symmetric top. If it does not
have a threefold or higher axis of
symmetry it is an asymmetric top.
All linear molecules (and hence all
diatomic molecules) are linear
rotors.
In reality, molecules are not rigid
rotors because of the centrifugal
forces associated with the rotation.
The effect of such forces can be
taken into account by adding a correction term to the rigid rotor model.
monatomic molecule A ‘molecule’ consisting of only one atom
(e.g. Ar or He), distinguished from diatomic and polyatomic molecules.
Mond process A method of obtaining pure nickel by heating the impure metal in a stream of carbon
monoxide at 50–60°C. Volatile nickel
carbonyl (Ni(CO) 4 ) is formed, and this
can be decomposed at higher temperatures (180°C) to give pure nickel.
The method was invented by the German–British chemist Ludwig Mond
(1839–1909).
Monel metal An alloy of nickel
(60–70%), copper (25–35%), and small
quantities of iron, manganese, silicon, and carbon. It is used to make
acid-resisting equipment in the
chemical industry.
monobasic acid An *acid that has
only one acidic hydrogen atom in its
molecules. Hydrochloric (HCl) and nitric (HNO 3 ) acids are common examples.
monoclinic See crystal system.
monoethanolamine See
ethanolamine.
monoglyceride See glyceride.
monohydrate A crystalline compound having one mole of water per
mole of compound.
monomer A molecule (or compound) that joins with others in
forming a dimer, trimer, or polymer.
monosaccharide (simple sugar) A
carbohydrate that cannot be split
into smaller units by the action of dilute acids. Monosaccharides are
classiÜed according to the number of
carbon atoms they possess: trioses
have three carbon atoms; tetroses,
four; pentoses, Üve; hexoses, six; etc.
Each of these is further divided into
aldoses and ketoses, depending on
whether the molecule contains an
aldehyde group (–CHO) or a ketone
group (–CO–). For example glucose,
having six carbon atoms and an aldehyde group, is an aldohexose
whereas fructose is a ketohexose.
These aldehyde and ketone groups
confer reducing properties on monosaccharides: they can be oxidized to
yield sugar acids. They also react
with phosphoric acid to produce
phosphate esters (e.g. in *ATP),
which are important in cell metabolism. Monosaccharides can exist as either straight-chain or ring-shaped
molecules. They also exhibit *optical
activity, giving rise to both dextrorotatory and laevorotatory forms.
monosodium glutamate (MSG) A
white solid, C 8 H 8 NNaO 4 .H 2 O, used
extensively as a Ûavour enhancer, especially in convenience foods. It is a
salt of glutamic acid (an *amino
acid), from which it is prepared. It
can cause an allergic reaction in
some susceptible people who consume it.
monotropy See allotropy.
monovalent (univalent) Having a
valency of one.
Monte Carlo method A numerical method for solving mathematical
and physical problems that involves
the random sampling of numbers.
Applications of Monte Carlo methods
monatomic molecule
360
m
www.AzShimi.ir www.AzShimi.com
threefold or higher axis of symmetry
it is a symmetric top. If it does not
have a threefold or higher axis of
symmetry it is an asymmetric top.
All linear molecules (and hence all
diatomic molecules) are linear
rotors.
In reality, molecules are not rigid
rotors because of the centrifugal
forces associated with the rotation.
The effect of such forces can be
taken into account by adding a correction term to the rigid rotor model.
monatomic molecule A ‘molecule’ consisting of only one atom
(e.g. Ar or He), distinguished from diatomic and polyatomic molecules.
Mond process A method of obtaining pure nickel by heating the impure metal in a stream of carbon
monoxide at 50–60°C. Volatile nickel
carbonyl (Ni(CO) 4 ) is formed, and this
can be decomposed at higher temperatures (180°C) to give pure nickel.
The method was invented by the German–British chemist Ludwig Mond
(1839–1909).
Monel metal An alloy of nickel
(60–70%), copper (25–35%), and small
quantities of iron, manganese, silicon, and carbon. It is used to make
acid-resisting equipment in the
chemical industry.
monobasic acid An *acid that has
only one acidic hydrogen atom in its
molecules. Hydrochloric (HCl) and nitric (HNO 3 ) acids are common examples.
monoclinic See crystal system.
monoethanolamine See
ethanolamine.
monoglyceride See glyceride.
monohydrate A crystalline compound having one mole of water per
mole of compound.
monomer A molecule (or compound) that joins with others in
forming a dimer, trimer, or polymer.
monosaccharide (simple sugar) A
carbohydrate that cannot be split
into smaller units by the action of dilute acids. Monosaccharides are
classiÜed according to the number of
carbon atoms they possess: trioses
have three carbon atoms; tetroses,
four; pentoses, Üve; hexoses, six; etc.
Each of these is further divided into
aldoses and ketoses, depending on
whether the molecule contains an
aldehyde group (–CHO) or a ketone
group (–CO–). For example glucose,
having six carbon atoms and an aldehyde group, is an aldohexose
whereas fructose is a ketohexose.
These aldehyde and ketone groups
confer reducing properties on monosaccharides: they can be oxidized to
yield sugar acids. They also react
with phosphoric acid to produce
phosphate esters (e.g. in *ATP),
which are important in cell metabolism. Monosaccharides can exist as either straight-chain or ring-shaped
molecules. They also exhibit *optical
activity, giving rise to both dextrorotatory and laevorotatory forms.
monosodium glutamate (MSG) A
white solid, C 8 H 8 NNaO 4 .H 2 O, used
extensively as a Ûavour enhancer, especially in convenience foods. It is a
salt of glutamic acid (an *amino
acid), from which it is prepared. It
can cause an allergic reaction in
some susceptible people who consume it.
monotropy See allotropy.
monovalent (univalent) Having a
valency of one.
Monte Carlo method A numerical method for solving mathematical
and physical problems that involves
the random sampling of numbers.
Applications of Monte Carlo methods
monatomic molecule
360
m
www.AzShimi.ir www.AzShimi.com