crystalline structure. The term is also
often applied generally to organic
substances that are obtained by mining (e.g. coal, petroleum, and natural
gas) but strictly speaking these are
not minerals, being complex mixtures without deÜnite chemical formulas. Rocks are composed of
mixtures of minerals. Minerals may
be identiÜed by the properties of
their crystal system, hardness (measured on the Mohs’ scale), relative
density, lustre, colour, cleavage, and
fracture. Many names of minerals
end in -ite.
mineral acid A common inorganic
acid, such as hydrochloric acid, sulphuric acid, or nitric acid.
mirabilite A mineral form of
*sodium sulphate, Na 2 SO 4 .10H 2 O.
misch metal An alloy of cerium
(50%), lanthanum (25%), neodymium
(18%), praseodymium (5%), and other
rare earths. It is used alloyed with
iron (up to 30%) in lighter Ûints, and
in small quantities to improve the
malleability of iron. It is also added
to copper alloys to make them
harder, to aluminium alloys to make
them stronger, to magnesium alloys
to reduce creep, and to nickel alloys
to reduce oxidation.
Mitscherlich’s law (law of isomorphism) Substances that have the
same crystal structure have similar
chemical formulae. The law can be
used to determine the formula of an
unknown compound if it is isomorphous with a compound of known
formula. It is named after Eilhard
Mitscherlich (1794–1863).
mixture A system of two or more
distinct chemical substances. Homogeneous mixtures are those in which
the atoms or molecules are interspersed, as in a mixture of gases or in
a solution. Heterogeneous mixtures
have distinguishable phases, e.g. a
mixture of iron Ülings and sulphur.
In a mixture there is no redistribution of valence electrons, and the
components retain their individual
chemical properties. Unlike compounds, mixtures can be separated
by physical means (distillation, crystallization, etc.).
m.k.s. units A *metric system of
units devised by A. Giorgi (and sometimes known as Giorgi units) in 1901.
It is based on the metre, kilogram,
and second and grew from the earlier *c.g.s. units. The electrical unit
chosen to augment these three basic
units was the ampere and the permeability of space (magnetic constant)
was taken as 10
–7 Hm
–1 . To simplify
electromagnetic calculations the
magnetic constant was later changed
to 4π × 10
–7 Hm
–1 to give the rationalized MKSA system. This system, with
some modiÜcations, formed the basis
of *SI units, now used in all scientiÜc
work.
mmHg A unit of pressure equal to
that exerted under standard gravity
by a height of one millimetre of mercury, or 133.322 pascals.
mobility (of an ion) Symbol u. The
terminal speed of an ion in an electric Üeld divided by the Üeld strength.
mode The pattern of motion in a vibrating body. If the body has several
component particles, such as a molecule consisting of several atoms, the
modes of vibration are the different
types of molecular vibrations possible.
moiety A characteristic part of a
molecule. For example, in the ester
C 2 H 5 COOCH 3 , the OCH 3 can be regarded as the alcohol (methanol)
moiety.
moissanite A clear form of silicon
carbide used as an inexpensive substitute for diamond. It is named after
mineral acid
356
m
www.AzShimi.ir www.AzShimi.com
often applied generally to organic
substances that are obtained by mining (e.g. coal, petroleum, and natural
gas) but strictly speaking these are
not minerals, being complex mixtures without deÜnite chemical formulas. Rocks are composed of
mixtures of minerals. Minerals may
be identiÜed by the properties of
their crystal system, hardness (measured on the Mohs’ scale), relative
density, lustre, colour, cleavage, and
fracture. Many names of minerals
end in -ite.
mineral acid A common inorganic
acid, such as hydrochloric acid, sulphuric acid, or nitric acid.
mirabilite A mineral form of
*sodium sulphate, Na 2 SO 4 .10H 2 O.
misch metal An alloy of cerium
(50%), lanthanum (25%), neodymium
(18%), praseodymium (5%), and other
rare earths. It is used alloyed with
iron (up to 30%) in lighter Ûints, and
in small quantities to improve the
malleability of iron. It is also added
to copper alloys to make them
harder, to aluminium alloys to make
them stronger, to magnesium alloys
to reduce creep, and to nickel alloys
to reduce oxidation.
Mitscherlich’s law (law of isomorphism) Substances that have the
same crystal structure have similar
chemical formulae. The law can be
used to determine the formula of an
unknown compound if it is isomorphous with a compound of known
formula. It is named after Eilhard
Mitscherlich (1794–1863).
mixture A system of two or more
distinct chemical substances. Homogeneous mixtures are those in which
the atoms or molecules are interspersed, as in a mixture of gases or in
a solution. Heterogeneous mixtures
have distinguishable phases, e.g. a
mixture of iron Ülings and sulphur.
In a mixture there is no redistribution of valence electrons, and the
components retain their individual
chemical properties. Unlike compounds, mixtures can be separated
by physical means (distillation, crystallization, etc.).
m.k.s. units A *metric system of
units devised by A. Giorgi (and sometimes known as Giorgi units) in 1901.
It is based on the metre, kilogram,
and second and grew from the earlier *c.g.s. units. The electrical unit
chosen to augment these three basic
units was the ampere and the permeability of space (magnetic constant)
was taken as 10
–7 Hm
–1 . To simplify
electromagnetic calculations the
magnetic constant was later changed
to 4π × 10
–7 Hm
–1 to give the rationalized MKSA system. This system, with
some modiÜcations, formed the basis
of *SI units, now used in all scientiÜc
work.
mmHg A unit of pressure equal to
that exerted under standard gravity
by a height of one millimetre of mercury, or 133.322 pascals.
mobility (of an ion) Symbol u. The
terminal speed of an ion in an electric Üeld divided by the Üeld strength.
mode The pattern of motion in a vibrating body. If the body has several
component particles, such as a molecule consisting of several atoms, the
modes of vibration are the different
types of molecular vibrations possible.
moiety A characteristic part of a
molecule. For example, in the ester
C 2 H 5 COOCH 3 , the OCH 3 can be regarded as the alcohol (methanol)
moiety.
moissanite A clear form of silicon
carbide used as an inexpensive substitute for diamond. It is named after
mineral acid
356
m
www.AzShimi.ir www.AzShimi.com