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Theorized the existence of atoms but was rejected by Aristotle and many others
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Discovered the Law of Conservation of Mass where matter cannot be created or destroyed
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Discovered all matter was made of atoms which are indestructible and unchangeable, different from Democritus's theory
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Discovered electrons and came up with the "plum pudding" model of the atom where negative particles were located in a positive atom
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Discovered polonium and radium which were more radioactive than uranium, proving atoms were not as stable and invariable as once thought to be
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The originator of quantum theory which helped further understanding of atomic processes
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Explained the photoelectric effect where electrons are ejected when light hit a metal plate a certain way and experimentally proved the existence of atoms and calculated their size by analyzing how tiny particles moved when suspended in water
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Determined the specific charge of electrons with his "oil drop" experiment
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His "gold foil" experiment allowed him to discover the nucleus which was positively charged with electrons floating in the empty space around it, replaced Thomson's "plum pudding" model
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Proposed that electrons orbited in set levels away from the nucleus, which led to his "planetary" model, electrons emit energy when it drops to a level closer to the nucleus and absorb energy when it gets further away
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Predicted the wave nature of electrons based on Einstein's theory
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Introduced quantum mechanics in the atomic theory which led to the discovery of allotropic forms of hydrogen, cannot prove Bohr's planetary orbits of electrons actually exist
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Used mathematical equations to predict the location of electrons based on De Broglie's theory and created the quantum mechanical model of the atom
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Proved the existence of the neutron which had no electrical charge by bombarding beryllium atoms with alpha particles
