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History of people who discovered the atom.
|440 BCE||Democritus: Atoms are uncuttable Atoms are small, hard particles.Atoms are made of a single material and are diff. shapes and sizes|
|1803||Dalton: Atoms of different elements are different. Atoms of the same element are exactly alike All substances are made of atoms Conducted experiments in combining elements|
|1897||Thomson: There are small, negatively charged particles inside an atom.Theory of atomic structure led to the plum-pudding model. Conducted cathode-ray tube experiment|
|1909-1911||Rutherford: Most of an atom's mass is in the nucleus. There is a small, dense, positively charged nucleus. Atoms contain mostly empty space. Model had electrons surrounding the nucleus at a distance|
|1913||Bohr: Electrons can jump from a path in one level to a path in another level.Electrons travel in certain paths, or energy levels|
|20th Century||Schrodinger/Heisenberg: Electron paths cannot be predicted.Electrons are found in electron clouds, not paths|