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460 BCE
Democritus
Democritus said all atoms are uncuttable , atoms are small hard particles, and atoms constantly move. -
Dalton
Dalton said all substances are made of atoms, atoms of different elements are different, atoms of the same elements are exactly alike, elements combine in specific proportion, and he conducted experiments in combining elements. -
Rutherford
Rutherford had a theory that atoms contain mostly empty space, that electrons move empty space in the atom, he conducted the gold foil experiment , most of the mass is in the nucleus and that there is small ,dense, positively charge in nucleus. -
bohr
Bohr said electrons jumps between levels from path to path, and elections travel in definite paths. -
Schrodinger and Heisenberg
said electron paths cannot be predicted, and electrons are found in electron clouds , not path. -
thomson
tomoson conducted the cathode-ray tube experiment, and his theory lead to the "plum-pudding" model