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Democritus was a greek philospher during 460 BC- 370 BC and he believed that atoms were invisble and indestructable. His ideas didn't have any scientifc evidence behind it.
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Dalton's model transformed Democritus idea into a scientific theory that was experimentally base.
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JJ Thompson discovered the Electron
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Thompson discovered the electron in 1904 using a cathode ray tube. He thought the atom was a positvely charged sphere, with negatively charged electrons.
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Rutherford said that an atom was mostly empty space with anucleus that is very small, dense, and is postively charged. He also said that electrons were distributed around the nucleus and that occupies most of the space
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Bohr bulit off the idea of Rutherford's idea and Bohr sais that electrons traveld in fixed orbitals areound the nucleus. Bohr had help from his students and they concluded that the nucleus had protons and electrons in it.
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Protons were discovered by Ernest Rutherford
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The Electron Cloud Model says that the electrons don't have fixed orbits, they have uncertain orbits that vary. Werner Heisenberg and Erwin Schrödinger came up with this idea from the principle that it is impossible to know the momentum and the location of a particle at the same time.
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Chadwick Discovered the neutron
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The Electron cloud model is the one that is widely used today
