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Period: 322 to
Scientist Timeline Project
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460
Democritus
Proposed that the world is made up of tiny particles called atoms and empty space; believed that atoms were the smallest particle of matter and the idea that matter is made up of atoms (Atomic Theory of matter) -
Robert Boyle
Separated chemistry from alchemy and gave the first definitions to chemical element, chemical reaction and chemical analysis. -
Antoine Lavoisier
Father of Modern Chemistry, First law of conservation of mass, recognized and named oxygen and hydrogen -
John Dalton
First useful atomic theory of mass in 1803, propsed homogenous spheres or the billiard ball model of atoms -
William Crookes
Discovered that cathode rays impart a negative charge to objects that they strike -
Eugene Goldstein
Discovered Protons through observations of cathode rays which he noted emited a glow near the ends which suggested energy extending from a negative electrode -
J.J. Thompson
Discovered the electron through experiments with a cathode ray tube and propsed the plum pudding model -
Robert Milikan
performed oil drop experiment which measured the electric charge of an atom -
Ernest Rutherford
Father of Nuclear Physics, discovered the nucleus through the gold foil experiment and proposed a nuclear model of the atom -
Neils Bohr
Danish Physicist, contributed to atomic structure by applying quantum theory to Rutherford's atomic structure and creating the planetary model of the atom -
James Chadwick
Proved the existence of neutrons -
Aristotle
Fundamental theory of matter that four elements (earth, air, fire, water) formed matter
