implosion An inward collapse of a
vessel, especially as a result of evacuation.
IMS See ion-mobility spectrometry.
incandescence The emission of
light by a substance as a result of
raising it to a high temperature.
InChI A type of *line notation introduced by IUPAC. The acronym stands
for International Chemical IdentiÜer.
Originally, it was IChI (IUPAC chemical identiÜer). An InChI can give a
large amount of chemical information displayed in layers and sublayers
separated by forward slashes. For example, the InChI for naphthalene is
InChI=1/C10H8/c-1-2-6-10-8-4-3-79(10)5-1/h1-8H
Here, InChI=1 indicates the version
of InChI used. The remainder of the
string is the main layer. It consists of
three sublayers. These are (1) the molecular formula (C 10 H 8 ); (2) the atomconnection information (starting
with c), and (3) the hydrogens present (starting with h). Other layers
can be added for such information as
charge, stereochemistry, and isotopic
composition.
A
• An FAQ produced by the Chemistry
Department, Cambridge University
• Information and downloads from the
IUPAC site
incommensurate lattice A lattice
with long-range periodic order that
has two or more periodicities in
which an irrational number gives the
ratio between the periodicities. An
example of an incommensurate lattice occurs in certain magnetic systems in which the ratio of the
magnetic period to the atomic lattice
is an irrational number. The phase
transition between a commensurate
lattice and an incommensurate lattice can be analysed using the
*Frenkel–Kontorowa model.
indene A colourless Ûammable hydrocarbon, C 9 H 8 ; r.d. 0.996; m.p.
–1.8°C; b.p. 182.6°C. Indene is an
aromatic hydrocarbon with a Üvemembered ring fused to a benzene
ring. It is present in coal tar and is
used as a solvent and raw material
for making other organic compounds.
independent-particle model A
model for electrons in a manyelectron system in which the correlation between electrons is either
ignored or taken into account by regarding an electron as moving in an
averaged-out potential that represents the interactions between the
electron and all the other particles in
the system. Although the independent-particle model cannot describe
all aspects of many-electron systems,
it had some notable successes, such
as explaining the shell structure of
electrons in atoms.
indeterminacy See uncertainty
principle.
indicator A substance used to show
the presence of a chemical substance
or ion by its colour. Acid–base indicators are compounds, such as phenolphthalein and methyl orange,
that change colour reversibly, depending on whether the solution is
acidic or basic. They are usually weak
acids in which the un-ionized form
HA has a different colour from the
negative ion A
– . In solution the indicator dissociates slightly
HA ˆ H
+ + A
–
In acid solution the concentration of
H
+ is high, and the indicator is
largely undissociated HA; in alkaline
solutions the equilibrium is displaced
to the right and A
– is formed. Useful
acid–base indicators show a sharp
colour change over a range of about
implosion
282
i
www.AzShimi.ir www.AzShimi.com
vessel, especially as a result of evacuation.
IMS See ion-mobility spectrometry.
incandescence The emission of
light by a substance as a result of
raising it to a high temperature.
InChI A type of *line notation introduced by IUPAC. The acronym stands
for International Chemical IdentiÜer.
Originally, it was IChI (IUPAC chemical identiÜer). An InChI can give a
large amount of chemical information displayed in layers and sublayers
separated by forward slashes. For example, the InChI for naphthalene is
InChI=1/C10H8/c-1-2-6-10-8-4-3-79(10)5-1/h1-8H
Here, InChI=1 indicates the version
of InChI used. The remainder of the
string is the main layer. It consists of
three sublayers. These are (1) the molecular formula (C 10 H 8 ); (2) the atomconnection information (starting
with c), and (3) the hydrogens present (starting with h). Other layers
can be added for such information as
charge, stereochemistry, and isotopic
composition.
A
• An FAQ produced by the Chemistry
Department, Cambridge University
• Information and downloads from the
IUPAC site
incommensurate lattice A lattice
with long-range periodic order that
has two or more periodicities in
which an irrational number gives the
ratio between the periodicities. An
example of an incommensurate lattice occurs in certain magnetic systems in which the ratio of the
magnetic period to the atomic lattice
is an irrational number. The phase
transition between a commensurate
lattice and an incommensurate lattice can be analysed using the
*Frenkel–Kontorowa model.
indene A colourless Ûammable hydrocarbon, C 9 H 8 ; r.d. 0.996; m.p.
–1.8°C; b.p. 182.6°C. Indene is an
aromatic hydrocarbon with a Üvemembered ring fused to a benzene
ring. It is present in coal tar and is
used as a solvent and raw material
for making other organic compounds.
independent-particle model A
model for electrons in a manyelectron system in which the correlation between electrons is either
ignored or taken into account by regarding an electron as moving in an
averaged-out potential that represents the interactions between the
electron and all the other particles in
the system. Although the independent-particle model cannot describe
all aspects of many-electron systems,
it had some notable successes, such
as explaining the shell structure of
electrons in atoms.
indeterminacy See uncertainty
principle.
indicator A substance used to show
the presence of a chemical substance
or ion by its colour. Acid–base indicators are compounds, such as phenolphthalein and methyl orange,
that change colour reversibly, depending on whether the solution is
acidic or basic. They are usually weak
acids in which the un-ionized form
HA has a different colour from the
negative ion A
– . In solution the indicator dissociates slightly
HA ˆ H
+ + A
–
In acid solution the concentration of
H
+ is high, and the indicator is
largely undissociated HA; in alkaline
solutions the equilibrium is displaced
to the right and A
– is formed. Useful
acid–base indicators show a sharp
colour change over a range of about
implosion
282
i
www.AzShimi.ir www.AzShimi.com