-
460
Democritus
460b.c 370 b.c
atoms indestructible, thought there was an 'atom'
thought atoms were just balls -
Oct 1, 600
Thales of Miletus
600B.C
Everything came from water
no atomic, no experiences -
Sir Issac Newton
thought all atoms moved around
no atomic modek
no experiment -
John Dalton
Element made extremely small particles
Atoms given element, identical in size,mass. Atoms different elements
Atom different elements combine in whole number ratios, form chemical compound -
Henri Becquerel
discovred radioactivity
atom was a solid ball -
J.J Thomson
1897-discoverd electon 2,000 lighter than hydrogen atom
experiment cathade rays tube
plum pudding -
Ernst Rutherford
Discoverd nusleuc in atoms
atoms contained nucelus, protons, surrounded by electrons -
Robert Millikan
1908-1917
oil drop experiment
discoverd charge and mass each element -
Bohr
Bohr Model created electrons in atom, orbits energy around nueleus.
Bohr Theory not all correct -
Francis Aston
Found isotope using a mass spectrometer
formulated whole nuber rule -
James Chadwick
Discoverd evidence toward existance of heutrons -
Aristotle
384b.c -322 b.c
not believe atomic theory