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Democritus believed that there were indivisible particles; all matter was made up of these atoms. He thought each atom had unique properties.
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Dalton believed that the atom is an indestructible sphere that has no concept of internal structure all the way through.
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Thomson came up with the idea that the atom consists of positively charged material filled with tiny negatively charged particles - kind of like plum pudding.
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Rutherford and Bohr believe that in an atom, thh epositively charged material is in a tiny nucleus in the centre and the negatively charged electtrons move around it in indefinite circular orbits and the rest is empty space.
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Schroedinger said that since electrons are continuously circling the nucleus in the atoms, they form complex regions that look like "clouds". This led to the electron clooud model.
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Aristotle believed all matter was made up of the four elements – air, water, fire, earth which were made up of particles with specific properties.
