Modern chemistry
arose in the period between 1770 and 1800, due mainly to the efforts
of a French chemist named Lavoisier. Lavoisier eliminated phlogiston and introduced the concept of elements as the fundamental substances
of chemistry. He reformed chemical nomenclature and encouraged quantitative measurements
in chemical practice.
Lavoisier's oxygen
theory of combustion "set chemistry
on a fruitful path" (17) and
was the beginning of the chemical
revolution. Just as important was his publication of Traité élémentaire
do chimie in 1879 -- the first textbook of the "new chemistry."
The Phlogiston Theory
The phlogiston theory was intorduced by Becher (1635-1682)
and developed by his disciple, Stahl (1660-1734). This was
an important theory--one of the first generalizations in
chemistry that correlated in a simple manner many chemical
phenomena. According to the phlogiston theory, combustion
was due to loss of phlogiston [φ]. For instance, this
theory would interpret carbon as high in phlogiston. When
carbon burns, it loses its phlogiston.
As one example, it offered an explanation of why combustion
eventually stops in a closed container. As combustion
proceeds, the air in the container fills up with phlogiston.
When the air becomes saturated with phlogiston, compustion
ceases.
The Oxygen Theory
According to the oxygen theory, air contains
a gas called "oxygen", which is a chemical element involved
in combustion. For instance, when carbon burns it reacts
with oxygen in the air. We now write this as
C + O2 ----> CO2
The realization of the importance of oxygen was a "death
blow to the concept of air and water elements" [17].
