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Thales of Miletus
600 B.C.
Declared everything is made of water. -
Democritus
460 - 370 B.C.
Thought everything was made of atoms. -
Aristotle
384 - 322 B.C.
Thought everything was earth, water, air, and fire -
Sir Isaac Newton
1704
Thought that atoms moved around and were small -
Dalton
1803
Found the properties in gases and matter -
Becquerel
1896/1897
Discovered radioactivity -
J. J. Thomson
1897
He discovered the electron -
Ernest Ruthaford
1904-1911
Atoms contain a nucleus made of protons surrounded by electrons -
Gold Foil Experiment
Ruthaford fired helium atoms at a gold sheet of paper but they hit the nucleus and bounced back. He didn't think they would. -
Francis Aston
1922
Discovered and studied isotopes. Also did the whole number rule. -
Bohr
1915
Created Bohr model and said everything was on fixed path's and couldn't be inbetween. -
Schrodinger
1926
Used math equations to describe where electrons will probably be -
James Chodwick
1932
Discovered evidence towrds the existance of Neutrons -
Robert Milikan
1908 -1917
Determined the charge and mass of an electron