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Atomic Theory
Scientist Facts
| Question | Answer |
|---|---|
| 440 B.C. | Democritus |
| Atoms are uncuttable | Democritus |
| "Atomos" meaning indivisible | Democritus |
| 1803 | Dalton |
| Atoms of different elements are different | Dalton |
| Conducted experiment combining elements; elements combine in proportions | Dalton |
| All substances are made of atoms | Dalton |
| Atoms of the same element are exactly alike | Dalton |
| 1897 | Thomson |
| Small, negatively charged particles inside the atom | Thomson |
| Cathode Ray Tube Experiment | Thomson |
| Plum Pudding Model | Thomson |
| 1911 | Rutherford |
| Small, dense positively charged nucleus | Rutherford |
| Most of an atom's mass is in the nucleus | Rutherford |
| Atoms contain mostly empty space | Rutherford |
| Electrons travel around nucleus like planets | Rutherford |
| Gold Foil Experiment | Rutherford |
| 1913 | Bohr |
| Electrons jump between levels from path to path | Bohr |
| Electrons travel in definite paths | Bohr |
| Electron paths are called levels | Bohr |
| Twentieth century | Heisenberg and Schrodinger |
| Electrons are found in electron clouds not paths | Heisenberg and Schrodinger |
| Electron paths cannot be predicted | Heisenberg and Schrodinger |
| Atoms cannot be created, divided, or destroyed | Dalton |
| Levels are certain distances from the nucleus | Bohr |
| No paths are located between levels | Bohr |
| Inside the nucleus is the protons | Heisenberg and Schrodinger |