I
ice See water.
ice point The temperature at
which there is equilibrium between
ice and water at standard atmospheric pressure (i.e. the freezing or
melting point under standard conditions). It was used as a Üxed point (0°)
on the Celsius scale, but the kelvin
and the International Practical Temperature Scale are based on the
*triple point of water.
icosahedron A polyhedron having
20 triangular faces with Üve edges
meeting at each vertex. The symmetry of an icosahedron (known as
icosahedral symmetry) has Üvefold rotation axes. It is impossible in *crystallography to have a periodic crystal
with the point group symmetry of an
icosahedron (icosahedral packing).
However, it is possible for shortrange order to occur with icosahedral
symmetry in certain liquids and
glasses because of the dense packing
of icosahedra. Icosahedral symmetry
also occurs in certain *quasicrystals,
such as alloys of aluminium and
manganese.
ideal crystal A single crystal with a
perfectly regular lattice that contains
no impurities, imperfections, or
other defects.
ideal gas (perfect gas) A hypothetical gas that obeys the *gas laws exactly. An ideal gas would consist of
molecules that occupy negligible
space and have negligible forces between them. All collisions made between molecules and the walls of the
container or between molecules and
other molecules would be perfectly
elastic, because the molecules would
have no means of storing energy except as translational kinetic energy.
ideal solution See raoult’s law.
IE Ionization energy. See ionization
potential.
ignition temperature The temperature to which a substance must
be heated before it will burn in air.
Ilkovic equation A relation used
in polarography relating the diffusion current i a and the concentration
c. The Ilkovic equation has the form
i a = kc, where k is a constant.
imides Organic compounds containing the group –CO.NH.CO.– (the
imido group).
A
• Information about IUPAC nomenclature
imido group See imides.
imines Compounds containing the
group –NH– in which the nitrogen
atom is part of a ring structure, or
the group =NH, in which the nitrogen atom is linked to a carbon atom
by a double bond. In either case, the
group is referred to as an imino
group.
A
• Information about IUPAC nomenclature
imino group See imines.
Imperial units The British system
of units based on the pound and the
yard. The former f.p.s. system was
used in engineering and was loosely
based on Imperial units; for all
scientiÜc purposes *SI units are now
used. Imperial units are also being replaced for general purposes by metric units.
www.AzShimi.ir www.AzShimi.com
ice See water.
ice point The temperature at
which there is equilibrium between
ice and water at standard atmospheric pressure (i.e. the freezing or
melting point under standard conditions). It was used as a Üxed point (0°)
on the Celsius scale, but the kelvin
and the International Practical Temperature Scale are based on the
*triple point of water.
icosahedron A polyhedron having
20 triangular faces with Üve edges
meeting at each vertex. The symmetry of an icosahedron (known as
icosahedral symmetry) has Üvefold rotation axes. It is impossible in *crystallography to have a periodic crystal
with the point group symmetry of an
icosahedron (icosahedral packing).
However, it is possible for shortrange order to occur with icosahedral
symmetry in certain liquids and
glasses because of the dense packing
of icosahedra. Icosahedral symmetry
also occurs in certain *quasicrystals,
such as alloys of aluminium and
manganese.
ideal crystal A single crystal with a
perfectly regular lattice that contains
no impurities, imperfections, or
other defects.
ideal gas (perfect gas) A hypothetical gas that obeys the *gas laws exactly. An ideal gas would consist of
molecules that occupy negligible
space and have negligible forces between them. All collisions made between molecules and the walls of the
container or between molecules and
other molecules would be perfectly
elastic, because the molecules would
have no means of storing energy except as translational kinetic energy.
ideal solution See raoult’s law.
IE Ionization energy. See ionization
potential.
ignition temperature The temperature to which a substance must
be heated before it will burn in air.
Ilkovic equation A relation used
in polarography relating the diffusion current i a and the concentration
c. The Ilkovic equation has the form
i a = kc, where k is a constant.
imides Organic compounds containing the group –CO.NH.CO.– (the
imido group).
A
• Information about IUPAC nomenclature
imido group See imides.
imines Compounds containing the
group –NH– in which the nitrogen
atom is part of a ring structure, or
the group =NH, in which the nitrogen atom is linked to a carbon atom
by a double bond. In either case, the
group is referred to as an imino
group.
A
• Information about IUPAC nomenclature
imino group See imines.
Imperial units The British system
of units based on the pound and the
yard. The former f.p.s. system was
used in engineering and was loosely
based on Imperial units; for all
scientiÜc purposes *SI units are now
used. Imperial units are also being replaced for general purposes by metric units.
www.AzShimi.ir www.AzShimi.com