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Democritus was the first to discover the basics of an atom and determined they were too small to be seen.
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Medieval chemistry!
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He believed everything was made up of the four elements of the known world; water, fire, air, and earth.
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Robert Boyle discovered that the pressure of gas increases as the volume of the container decreases.
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John Dalton took Democritus's theory and made it into reality. He was the first to make a real model of an atom.
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Dmitri Mendeleev was the one who arranged the elements in order according to their mass.
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J.J. Thomson made the plum pudding model. He also thought that atoms had positive/ negative cores and theorized that atoms could be divided.
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Robert Milliken performed the oil drop experiment which determined the charge of an electron.
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Ernest Rutherford discovered that there is a electron cloud around the outside of the atom.
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Hans Geiger helped to discover individual particles.
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Neils Bohr created the Bohr model.
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James Chadwick discovered the neutron in the atom.
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