History of Chemistry

Aristotle

All matter is composed of earth, fire, air and water

Democritus

Matter is composed of “atomos” (meaning indivisible)

John Dalton

developed the modern atomic theory

J.J. Thomson

Discovered the election and the plum pudding or chocolate chip atom model.

Ernest Rutherford

determined atoms were mostly empty space through his gold foil experiment, discovered the nucleus, discovered the nucleus was positively charged

Henry Moseley

determined the atomic numbers for elements

Robert Millikan

determined charge of a single electron

James chadwick

discovered the neutron

Wilhem Roentgen

discovered x-rays and

Pierre Curie

Co-discovered radioactivity

Marie Curie

Co-discovered radioactivity, discovered radium and polonium

Henri Bequerel

Discovered radioactivity

Otto Hahn

Co-discovered nuclear fission

Lise Meitner

Co-discovered nuclear fission