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440 BCE
Democritus
Atoms are "uncuttable", All substances are made of atoms, Atoms are small, hard particles -
440 BCE
Democritus
Atomic Model -
Period: 440 BCE to
Atomic Theory Timeline
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John Dalton
Atoms of different elements are different, Atoms of the same element are exactly alike, Elements combine in specific proportions, & he conducted experiments in combining elements -
John Dalton
Atomic Model -
J.J Thompson
He conducted the cathode-ray tube experiment, there are small, negatively charged particles inside an atom, & his theory of the atomic structure lead to the "plum-pudding" model -
J.J. Thompson
Atomic Model -
Ernest Rutherford
Atoms contain mostly empty space, most of an atom's mass is in the nucleus, there is a small, dense, positively charged nucleus, & conducted the gold foil experiment -
Ernest Rutherford
Atomic Model -
Niels Bohr
Electrons jump between levels from path and path, electrons move in an empty space in the atom, & electrons travel in definite paths -
Niels Bohr
Atomic Model -
Erwin Schrodinger and Werner Heisenberg
Electron paths cannot be predicted & electrons are found in electron clouds, not paths -
Erwin Schrodinger and Werner Heisenberg
Atomic Model
