Chemical Reactions
Chemical reactions are the heart of
chemistry. People have always known that
they exist. The Ancient Greeks were
the first to speculate on the composition of
matter. They thought that it was
possible that individual particles made up
matter. Later, in the Seventeenth
Century, a German chemist named George Ernst
Stahl was the first to
postulate on chemical reaction. He said that a substance
called phlogiston
escaped into the air from all substances during combustion. He
explained that
a burning candle would go out if a candle snuffer was put over it
because the
air inside the snuffer became saturated with phlogiston. Stahl also
said that
phlogiston will take away from a substance's mass or that it had a
negative
mass, which contradicted his original theories. In the Eighteenth
Century
Antoine-Laurent Lavoisier, in France, discovered an important detail in
the
understanding of the chemical reaction combustion, oxigine (oxygen). He
said
that combustion was a chemical reaction involving oxygen and another
combustible
substance, such as wood. John Dalton, in the early Nineteenth
Century,
discovered the atom. It led to the idea that a chemical reaction was
actually
the rearrangement of groups of atoms called molecules. Dalton also
said that the
appearance and disappearance of properties meant that the
atomic composition
dictated the appearance of different properties. He also
came up with idea that
a molecule of one substance is exactly the same as any
other molecule of the
same substance. People like Joseph-Lois Gay-Lussac
added to Dalton's ideas with
the postulate that the volumes of gasses that
react with each other are related.
Amedeo Avogadro also added to the
understanding of chemical reactions. He said
that all gasses at the same
pressure, volume and temperature contain the same
number of particles. This
idea took a long time to be accepted. His ideas lead
to the subscripts used
in the formulas for gasses. From the work of these and
many other chemists,
we now have a mostly complete knowledge of chemical
reactions. There are now
many classification systems to classify the different
types of reactions.
These include decomposition, polymerization, chain
reactions, substitute
reactions, elimination reactions, addition reactions,
ionic reactions, and
oxidation-reduction reactions.
Bibliography
"Chemical Reactions,"
Webster Encyclopedia. 1993. Eastman, Richard
H., General Chemistry:
Experimental and Theory, Holt, Rhinehart, and Winston
Inc., 1970 Pauling,
Linus and Peter, Chemistry, W. H. Freeman and Co.,