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Atomic History
History of people who discovered the atom.
| Question | Answer |
|---|---|
| 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 |