multidecker sandwich See sandwich compound.
multiple bond A bond between
two atoms that contains more than
one pair of electrons. Such bonds primarily involve sigma bonding with
secondary contribution from pi bonding (or, sometimes, delta bonding).
See orbital.
multiple proportions See chemical combination.
multiplet 1. A spectral line formed
by more than two (see doublet)
closely spaced lines. 2. A group of elementary particles that are identical
in all respects except that of electric
charge.
multiplicity A quantity used in
atomic *spectra to describe the energy levels of many-electron atoms
characterized by *Russell–Saunders
coupling given by 2S + 1, where S is
the total electron *spin quantum
number. The multiplicity of an energy level is indicated by a left superscript to the value of L, where L is the
resultant electron *orbital angular
momentum of the individual electron orbital angular momenta l.
multipole interactions Interactions between arrays of point charges
(multipoles) associated with potential
energies that depend on distance.
Multipole interactions are an important feature of intermolecular forces.
An n-pole is a set of n charges having
an n-pole moment but not a lower
moment. A monopole is a single
charge and the monopole moment is
the charge. A dipole consists of two
opposite charges and thus has no
overall charge (and hence no monopole moment). Higher multipoles are
the *quadrupole and the *octupole.
The interaction potential energy between multipoles falls off with distance increasingly rapidly as the
order of the multipoles increases. If a
2
m -pole interacts with a 2
n
-pole, the
interaction potential energy, V,
varies with distance r as V =
c/(r
m + n – 1 ), where c is a constant. The
rapid fall-off with distance, as the
order increases, is due to the set of
charges appearing to tend towards
neutrality (as seen from outside). The
multipole interactions with the
largest interactions are: ion–ion,
ion–dipole, dipole–dipole, and dispersion interactions.
Mumetal The original trade name
for a ferromagnetic alloy, containing
78% nickel, 17% iron, and 5% copper,
that had a high permeability and a
low coercive force. More modern versions also contain chromium and
molybdenum. These alloys are used
in some transformer cores and for
shielding various devices from external magnetic Üelds.
Muntz metal A form of *brass containing 60% copper, 39% zinc, and
small amounts of lead and iron.
Stronger than alpha-brass, it is used
for hot forgings, brazing rods, and
large nuts and bolts. It is named after
G. F. Muntz (1794–1857).
muscovite (white mica; potash
mica) A mineral form of potassium
aluminosilicate, K 2 Al 4 (Si 6 Al 2 )O 20 -
(OH,F) 4 ; one of the most important
members of the *mica group of minerals. It is chemically complex and
has a sheetlike crystal structure (see
intercalation compound). It is usually silvery-grey in colour, sometimes
tinted with green, brown, or pink.
Muscovite is a common constituent
of certain granites and pegmatites. It
is also common in metamorphic and
sedimentary rocks. It is widely used
in industry, for example in the manufacture of electrical equipment and
as a Üller in rooÜng materials, wallpapers, and paint.
363
muscovite
m
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multiple bond A bond between
two atoms that contains more than
one pair of electrons. Such bonds primarily involve sigma bonding with
secondary contribution from pi bonding (or, sometimes, delta bonding).
See orbital.
multiple proportions See chemical combination.
multiplet 1. A spectral line formed
by more than two (see doublet)
closely spaced lines. 2. A group of elementary particles that are identical
in all respects except that of electric
charge.
multiplicity A quantity used in
atomic *spectra to describe the energy levels of many-electron atoms
characterized by *Russell–Saunders
coupling given by 2S + 1, where S is
the total electron *spin quantum
number. The multiplicity of an energy level is indicated by a left superscript to the value of L, where L is the
resultant electron *orbital angular
momentum of the individual electron orbital angular momenta l.
multipole interactions Interactions between arrays of point charges
(multipoles) associated with potential
energies that depend on distance.
Multipole interactions are an important feature of intermolecular forces.
An n-pole is a set of n charges having
an n-pole moment but not a lower
moment. A monopole is a single
charge and the monopole moment is
the charge. A dipole consists of two
opposite charges and thus has no
overall charge (and hence no monopole moment). Higher multipoles are
the *quadrupole and the *octupole.
The interaction potential energy between multipoles falls off with distance increasingly rapidly as the
order of the multipoles increases. If a
2
m -pole interacts with a 2
n
-pole, the
interaction potential energy, V,
varies with distance r as V =
c/(r
m + n – 1 ), where c is a constant. The
rapid fall-off with distance, as the
order increases, is due to the set of
charges appearing to tend towards
neutrality (as seen from outside). The
multipole interactions with the
largest interactions are: ion–ion,
ion–dipole, dipole–dipole, and dispersion interactions.
Mumetal The original trade name
for a ferromagnetic alloy, containing
78% nickel, 17% iron, and 5% copper,
that had a high permeability and a
low coercive force. More modern versions also contain chromium and
molybdenum. These alloys are used
in some transformer cores and for
shielding various devices from external magnetic Üelds.
Muntz metal A form of *brass containing 60% copper, 39% zinc, and
small amounts of lead and iron.
Stronger than alpha-brass, it is used
for hot forgings, brazing rods, and
large nuts and bolts. It is named after
G. F. Muntz (1794–1857).
muscovite (white mica; potash
mica) A mineral form of potassium
aluminosilicate, K 2 Al 4 (Si 6 Al 2 )O 20 -
(OH,F) 4 ; one of the most important
members of the *mica group of minerals. It is chemically complex and
has a sheetlike crystal structure (see
intercalation compound). It is usually silvery-grey in colour, sometimes
tinted with green, brown, or pink.
Muscovite is a common constituent
of certain granites and pegmatites. It
is also common in metamorphic and
sedimentary rocks. It is widely used
in industry, for example in the manufacture of electrical equipment and
as a Üller in rooÜng materials, wallpapers, and paint.
363
muscovite
m
www.AzShimi.ir www.AzShimi.com