equally be deÜned as the energy required to increase the surface area
isothermally by one square metre,
i.e. it can be measured in joules per
metre squared (which is equivalent
to N m
–1
).
The property of surface tension is
responsible for the formation of liquid drops, soap bubbles, and meniscuses, as well as the rise of liquids in
a capillary tube (capillarity), the absorption of liquids by porous substances, and the ability of liquids to
wet a surface.
surfactant (surface active agent) A
substance, such as a *detergent,
added to a liquid to increase its
spreading or wetting properties by
reducing its *surface tension.
suspension A mixture in which
small solid or liquid particles are suspended in a liquid or gas.
SYBYL line notation A type of
line notation, similar to *SMILES but
with some additional features. In
SLN, hydrogens are not omitted, so
ethane is CH3CH3. Wild-card atoms
and groups can be speciÜed for
searching.
sylvite (sylvine) A mineral form of
*potassium chloride, KCl.
symmetric top See moment of inertia.
symmetry The property of an object that enables it to undergo certain manipulations, called symmetry
operations, such that its new state is
indistinguishable from its original
state. Examples include inversion
through a point, reÛection through a
plane, and rotation about an axis.
The geometrical feature of the object
with respect to which the symmetry
operation is carried out is termed a
symmetry element. In the above examples, a point through which inversion can be performed, a plane of
reÛection, and an axis of rotation are
the symmetry elements. See also molecular symmetry.
symmetry-adapted linear combinations See salc.
syn See torsion angle.
synchrotron radiation Electromagnetic radiation produced when
charged particles travel in a curved
path. In a generator of synchrotron
radiation, electrons are accelerated in
a synchrotron and injected into a
storage ring where they circulate at a
constant energy. Radiation can be
taken from the storage ring tangentially at various points around the
ring. The advantage of this type of
source is that it gives a narrow intense beam that is tunable to a particular wavelength over a whole
range from infrared radiation to hard
X-rays. Synchrotron radiation is used
for a variety of studies including crystallography, X-ray scattering, and ionization experiments.
synclinal See torsion angle.
syndiotactic See polymer.
syneresis The spontaneous separation of the solid and liquid components of a gel on standing.
synperiplanar See torsion angle.
synthesis The formation of chemical compounds from more simple
compounds.
synthesis gas See haber process.
synthetic Describing a substance
that has been made artiÜcially; i.e.
one that does not come from a natural source.
synthon A fragment obtained by
disconnection in *retrosynthetic
analysis. By analogy, units building
up structures by self-assembly in
*supramolecular chemistry are some515
synthon
s
www.AzShimi.ir www.AzShimi.com
isothermally by one square metre,
i.e. it can be measured in joules per
metre squared (which is equivalent
to N m
–1
).
The property of surface tension is
responsible for the formation of liquid drops, soap bubbles, and meniscuses, as well as the rise of liquids in
a capillary tube (capillarity), the absorption of liquids by porous substances, and the ability of liquids to
wet a surface.
surfactant (surface active agent) A
substance, such as a *detergent,
added to a liquid to increase its
spreading or wetting properties by
reducing its *surface tension.
suspension A mixture in which
small solid or liquid particles are suspended in a liquid or gas.
SYBYL line notation A type of
line notation, similar to *SMILES but
with some additional features. In
SLN, hydrogens are not omitted, so
ethane is CH3CH3. Wild-card atoms
and groups can be speciÜed for
searching.
sylvite (sylvine) A mineral form of
*potassium chloride, KCl.
symmetric top See moment of inertia.
symmetry The property of an object that enables it to undergo certain manipulations, called symmetry
operations, such that its new state is
indistinguishable from its original
state. Examples include inversion
through a point, reÛection through a
plane, and rotation about an axis.
The geometrical feature of the object
with respect to which the symmetry
operation is carried out is termed a
symmetry element. In the above examples, a point through which inversion can be performed, a plane of
reÛection, and an axis of rotation are
the symmetry elements. See also molecular symmetry.
symmetry-adapted linear combinations See salc.
syn See torsion angle.
synchrotron radiation Electromagnetic radiation produced when
charged particles travel in a curved
path. In a generator of synchrotron
radiation, electrons are accelerated in
a synchrotron and injected into a
storage ring where they circulate at a
constant energy. Radiation can be
taken from the storage ring tangentially at various points around the
ring. The advantage of this type of
source is that it gives a narrow intense beam that is tunable to a particular wavelength over a whole
range from infrared radiation to hard
X-rays. Synchrotron radiation is used
for a variety of studies including crystallography, X-ray scattering, and ionization experiments.
synclinal See torsion angle.
syndiotactic See polymer.
syneresis The spontaneous separation of the solid and liquid components of a gel on standing.
synperiplanar See torsion angle.
synthesis The formation of chemical compounds from more simple
compounds.
synthesis gas See haber process.
synthetic Describing a substance
that has been made artiÜcially; i.e.
one that does not come from a natural source.
synthon A fragment obtained by
disconnection in *retrosynthetic
analysis. By analogy, units building
up structures by self-assembly in
*supramolecular chemistry are some515
synthon
s
www.AzShimi.ir www.AzShimi.com