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Frist atomic theorist,Democritus knew that if a stone was divided in half, the two halves would have the same properties as the whole;therefore, he figured that if the stone were to be continually cut into smaller and smaller pieces then eventually there would be a piece that would be so small as to be indivisible.
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He created the first chart of atomic weights.
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Proposed the plum pudding model of the atom.
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He performed his gold foil experiment.
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Proposed a theory for the atom that energy is transferred only in certain well defined quantities. Electrons move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted.
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Used mathematical equations to describe the likelihood of finding an electron in a certain position.
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Bombarded beryllium atoms with alpha particles. An unknown radiation was produced. Chadwick interpreted this radiation as being composed of particles with a neutral electrical charge and the approximate mass of a proton. This particle became known as the neutron.
