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Democritus made a thoery that everything is made of a particale that cannot become simpler called atomos.
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John Dalton based a new theory called the atomic theory based on Democritus' atmoms theory. He said everything was made of spherical shaped solids called atoms.
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J.J Thompson used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram.
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Rutherford studied radiations emitted from uranium and thorium and named them alpha and beta.
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Rutherford using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil . He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus