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400
democritus
everything is made of indivisible particles called atoms -
john dalton
everything is made of atoms. they cant be broken down. atoms of each element are unique -
jj thompson
discovered electron. pudding model -
earnest rutherford
atoms are mostly space w/ small dense pos nucleus -
neils bohr
organized electrons into energy levels -
ernest rutherford
finds 1st evidence of proton -
arthur compton
comfirms photons as particles -
louis de broglie
propoes matter has wave properties -
wolfgang pauli
formulates exclusion principle for electrons in an atom -
walter bothe/hans geiger
demonstrates energy & mass are conserved in atomic processes -
erwin schroedinger
developes wave mechanics -
werner heisenberg
formulates uncertainty principle -
paul dirac
combines quantum mechanics & special relavitivty to describe electron -
wolfgang pauli
suggests neutrino to explain continuous electron spectrum for beta decay -
james chadwick
discovers neutron
