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Democritus came up with the idea that matter was made up of invisible particles called atoms.
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Aristotle believed that all matter wasn't made up of atoms, but of the four elements, earth, wind, water, and fire.
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Stated that atoms were specific to the thing they came from.
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Stated that matter could not be created or destroyed.
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Proposed a new atomic theory using spherical solid.
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Suggested model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces.
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Stated that the atom has a tiny, heated nucleus using the gold foil experiment.
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Discovered how to measure the charge of an electron.
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Discovered that electrons travel in separate orbits around the nucleus.
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Found out that electrons don't travel in neat orbits, and included quantum physics in the atomic theory.
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Used mathematical equations to describe the likelihood of finding an electron in a certain position.
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Discovered neutrons in the atom.