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400 BCE
Domocritus
The first known atomic theorist, he ground seashells into powder, which he believed were atoms, which all things are made of. -
John Dalton
John Dalton's atomic theory was that all things are made of atoms, which are indestructible, and that a mixture of atoms made compounds -
Period: to
Dmitri Mendeleev
Mendeleev was among the first to provide an accurate periodic table based on atomic mass, and, despite a few errors, correctly predicted the nature of several atoms that weren't discovered yet. -
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J. J. Thomson
Thomson discovered the electron with the cathode ray and magnet experiments, and believed these subatomic particles clung to the central mass of the atoms. -
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Ernest Rutherford
Rutherford proved the relative size inside an atom with his gold foil experiment, changing and improving Thomson's -
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Niels Bohr
Solved the problem of light emissions in the past theories by proposing the electrons had fixed orbits and levels, and light is emitted when those levels change -
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Henry Moseley
Modified the periodic table to count by number of protons, not by mass, which corrected Mendeleev's errors -
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Erwin Schrödinger
Schrödinger made the electron cloud model, which changed Bohr's fixed paths for electrons into larger orbitals.