animal charcoal See charcoal.
animal starch See glycogen.
anion A negatively charged *ion,
i.e. an ion that is attracted to the
*anode in *electrolysis. Compare
cation.
anionic detergent See detergent.
anionic resin See ion exchange.
anisotropic Denoting a medium in
which certain physical properties are
different in different directions.
Wood, for instance, is an anisotropic
material: its strength along the grain
differs from that perpendicular to
the grain. Single crystals that are not
cubic are anisotropic with respect to
some physical properties, such as the
transmission of electromagnetic radiation. Compare isotropic.
annealing A form of heat treatment applied to a metal to soften it,
relieve internal stresses and instabilities, and make it easier to work or
machine. It consists of heating the
metal to a speciÜed temperature for a
speciÜed time, both of which depend
on the metal involved, and then allowing it to cool slowly. It is applied
to both ferrous and nonferrous metals and a similar process can be applied to other materials, such as
glass.
annelation See annulation.
annulation A type of chemical reaction in which a ring is fused to a
molecule by formation of two new
bonds. Sometimes the term annelation is used. See also cyclization.
annulenes Organic hydrocarbons
that have molecules containing simple single rings of carbon atoms
animal charcoal
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a
[14]-Annulene
[18]-Annulene
H
[30]-Annulene
H
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Annulenes
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