History of Chemistry

Leucippos and Demokritos

coined the term "atomos" to describe small indivisible particles of matter. (Greek, 400 B.C.)

Alchemy

2000 years of pseudoscience in which some elements and mineral acids were discovered.

Georg Bauer

developed a systematic study of metals from ores. (German, 16th century)

Paracelsus

used minerals in medicinal applications. (Swiss, 16th century)

Robert Boyle

The "first" chemist who quantitatively studied gases and established the beginnings of the Scientific Method. (Anglo-Irish, 1600's)

Georg Stahl

proposed the idea that "phlogiston" flowed out of burning material. (German, late 1600's)

Joseph Priestly

was credited with the discovery of oxygen gas which was involved in the combustion process. (English, 1700's)

Antoine Lavoisier

used combustion to formulate the Law of Conversation of Mass. (French, 1700's) His experiments showed combustion involved oxygen and not phlogiston.

Joseph Proust

used quantitative experiments to determine the composition of compounds and proposed the Law of Definite Proportions. (French, Late 1700's)

John Dalton

formulated ideas about the atom and the relationship between element masses and compound ratios which led to the Law of Definite Proportions and eventually to Dalton's Atomic Theory. (English, late 1700's to early 1800's)

Joseph Gay-Lussac

studied the reactions of gases and measured the volumes of each gas that reacted to form new compounds. (French, Late 1700's to early 1800's)

Amadeo Avogadro

used Gay-Lussac's experimental evidence to propose that under constant temperature and pressure, equal volumes of different gases contain the same number of particles. This assumption is called Avogadro's hypothesis and was later proven to be true. (Italian, early 1800's)

J. J. Thompson

used electrical discharges in cathode ray tubes to postulate the existence of a negatively charged atomic particle, the electron. He also determined the mass-to-charge ratio of the electron. (English, late 1800's)

Robert Millikan

used oil drops and electrical charge in an experiment that determined the mass of an electron. (American, Early 1900's)

Henri Becquerel

discovered that some elements release high energy radiation which he called radioactivity. His studied led to the identification of alpha, beta and gamma radiation. (French, late 1800's)

Ernest Rutherford

used his famous gold foil experiment to propose the idea of the nuclear atom in which an atom has a dense core, the nucleus, filled with positive charge. Further experimentation led him to postulate the existence of the neutron.(British, Early 1900's)