-
100
Aristotle- 340 BC
Believed all substances were made of earth, air, fire, and water -
440
Democritus- 440 BCE
First person to make an atom theory and come up with the word "atom" -
Oct 4, 620
Thales- 620 BC
First person to investigate the atom -
Issace Newton- 1704
All atoms were held together by attractions or forces -
John Dalton- 1803
First one to have proof of an atom through an experiment -
Henry Bacquerel- 1896
Believed all atoms were found through radioactivity -
J.J. Thompson- 1897
First one to discover electrons -
Robert Milliken- 1908
found charge of individual electrons -
Gold foil experiment- 1910
Alpha particles fired through a thin gold sheet into a zinc sulfite sheet -
Rutherford- 1911
found the nucleus and proton -
Bohr- 1913
Believed electrons had a certain orbit -
Aston- 1919
came up with isotopes -
Schrodinger- 1926
had the probablity that an electron would be in a certain position. -
James Chadwick- 1932
He discovered the neutron
