Zumbahl: Chemistry 6
Chapter 2: Atoms, Molecules, and Ions
2.1 The Early History of Chemistry
·Greeks were the 1
to try to explain why chemical changes occur.
·They proposed that all matters was composed of four fundamental substance:
2. Earth4. Air
·Democritos and Leucippos used the term “atomos” (later became “atom”) to describe small,
individual indivisible particles.
- a pseudoscience that dominated 2000 years of chemical history.
·The fundamental of modern chemistry were laid in the 16
Century with the development of
systematic metallurgy (extraction of metals from ores) by a German, Georg Bauer.
·The first “chemist” to perform truly quantitative experiments was Robert Boyle.
·He carefully measured the relationship between pressure and volume of air.
·Published his book
The Skeptical Chymist
in 1661 and resulted in the birth of
quantitative sciences of physics and chemistry.
·The phenomenon of combustion evoked intense interest in the 17
·Georg Stahl, a German chemist, suggested that a substance he called “phlogiston” flowed out of
the burning material.
·He postulated that a substance burning in a closed container eventually stopped burning
because the air in the container became saturated with phlogiston.
·Joseph Priestley, an English clergyman and scientist, discovered oxygen gas.
·Found that oxygen gas supported the vigorous combustion and was thus
supposed to be low in phlogiston.
·Oxygen was originally called “dephlogisticated air”.
2.2 Fundamental Chemical Laws
·By the late 18
century, combustion had been studied extensively; the gases carbon dioxide,
nitrogen, hydrogen, and oxygen had been discovered.
·Antoine Lavoisier, a French chemist, finally explained the true nature of combustion.
·He, like Boyle, regarded measurement as the essential operation of chemistry.
·In his experiments, he carefully weighed the reactants and products of various
reactions, and suggested that mass is neither created nor destroyed.
Law of conservation of mass
- mass is neither created nor destroyed.
·This law became the basis for developments in chemistry in the
·His experiments showed that combustion involves oxygen, not phlogiston.
·He also discovered that life was supported by a process that also involved oxygen
and was similar in many ways to combustion.
·Published the first modern chemistry textbook,
Elementary Treatise on Chemistry
·Oxygen is from the French oxygène, meaning “generator of acid,” because it was initially
considered to be an integral part of all acids.
·Joseph Proust, a French chemist, showed that a given compound always contains exactly the
same proportion of elements by mass.
·Originally called “Proust’s law,” is now known as the