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.,