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Aristotle didn't believe that atoms existed. He thought that everything and everyone was made up of the natural elements in the earth such as water and fire.
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Democritus discovered the idea of molecules that everything is made of. This occured in 400 B.C.
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Dalton believes that mass is based upon small spherical atoms.
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Crookes discovers the element ,thallium, using the crookes tube.
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Mendeleev creates the first organized periodic table.
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J. J. Thomson discovered the electron using cathode rays with the Crookes Tube.
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Rutherford discovers a positive force inside the nucleus of the atom.
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Chadwick discovers the neutron after noticing a strange amount of mass that protons and electrons were not taking up.
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