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Democritus was a Greek philosopher who discovered that there was a void between atoms and that atoms are different sizes
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carried out a minute investigation of thallium and its properties once he discovered it
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law of constant composition, law of multiple proportions, developed first useful atomic theory, 1st to associate atoms with stoichiometry
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studied canal rays, discovered that atoms were associated with the proton H+
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showed there were small charged particles called electrons, "developed the picture of an atom as a sphere of positive charge, occupying the whole volume of the atom, with electrons embedded in it.”
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"Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm)gold foil .” and “Using x-ray tubes, determined the charges on the nuclei of most atoms.”, assumed electrons were outside the nucleus, discovered nucleus was small dense and positively charged
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Bohr proposed tha the hydrogen atom was one heavy proton with a lighter electron orbiting it, discovered that only certain orbits are permitted, electrons would not create radio waves, changing the orbit of an electron could change the color
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”Schrödinger and Werner Heisenburg (1901-1976) mathematically determined regions in which electrons would be most likely found"
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used alpha particles to discovered a neutron atomic particle with a mass close to the proton, discovered neutron
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The currently used atomic model is the electron cloud model however the Bohr model may be used when it is convenient
