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