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400 BCE
Democritus
He conducted experiments in combining elements, atoms are small, hard particles, atoms constantly move. -
John Dalton
All substances are made of atoms, Atoms are uncuttable, Atoms of different elements are different, Atoms of the same element are exactly alike, Elements combine in specific proportions. -
Erwin Schrӧdinger
Electron paths cannot be predicted, Electrons are found in electron clouds, not paths. -
Werner Heisenberg
Electron paths cannot be predicted, Electrons are found in electron clouds, not paths. -
J.J. Thomson
He conducted the cathode-ray tube experiment, His theory of the atomic structure lead to the “plum-pudding” model, There are small, negatively charged particles inside an atom. -
Ernest Rutherford
Electrons move in empty space in the atom, He conducted experiments in combining elements, He conducted the gold foil experiment, Most of an atom’s mass is in the nucleus, There is a small, dense, positively charged nucleus. -
Niels Bohr
Electrons jump between levels from path to path, Electrons travel in definite paths.
