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Democritus suggested the first atomic theory, explaining that all things are "composed of minute, invisible, indestructible particles of pure matter which move about eternally in infinite empty."
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He made inferences in the 19th century that exhibited how atoms bond together in definite proportions
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He was credited for discovering the electron, ended up contributing to more than the atomic theory.
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He discovered the proton using the "gold foil" experiment and that atoms are composed of mostly empty space.
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He made the "Bohr Theory of the Atom". This theory was the closest to the modern atomic theory re-emphasized the idea of electrons around the nucleus. Bohr suggested that electrons orbited around the nucleus in seven different quantum levels, or shells.
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United States physicist, noted for his classification of subatomic particles and his proposal of the existence of quarks.
