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Period: 370 to 460
Democritus (460-370B.C.)
Democritus was the first to suggest that matter could not be infinetly divided. Democrtis also stated that atoms can not created, destroyed or further divided. -
Period: 500 to 565
Aristotle(384- 322 B.C)
Aristotle disagreed with Democritus about atmos moving through empty space. He denied the existecnce of atoms completly on behalf of his personal idea. -
Period: to
John Dalton
Dalton took the ideas of Democratis ideas about matter and revised them. He thought atoms are the smallest particles of matter. He also thought they were indivisible and indestructible. -
Period: to
William Crookes
Crookes noticed a green flash of light within a cathrode ray tube while in a dark laboratory. -
Period: to
J.J. Thompson
Thompson discovered the electrons, the first subatomic particle. He disproved Dalton's thoery that atoms are indivisible. He also was awarded the Nobel Prize in 1906. He is known for his plum pudding model. -
Period: to
Robert Milikan
To determine the charge of electrons Milikan designed an oil drop apparatus. He determined the mass of an electron and also it's magnitude. -
Period: to
Ernest Rutherford
Studied positively charged particles and proved the plum pudding model wrong. He is also known for discovering the nucleus and protons. -
Period: to
James Chadwick
Chadwick discovered the neutron and recieved the Nobel Prize in 1903.