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465
Democritus
Democritus hypothesized that atoms cannot be destroyed, differ in size, shape and temperature, are always moving, and are invisible. -
465
Democritus
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John Dalton
His theory said all matter is made of atoms, atoms are indivisible and indestructible, all atoms of a given element are identical in mass and properties, compounds are formed by a combination of two or more different kinds of atoms, and a chemical reaction is a rearrangement of atoms. -
John Dalton
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J. J. Thompson
He discovered the electron. -
J. J. Thompson
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Robert Milliken
Measured the charge of the electron using an oil drop experiment. -
Robert Milliken
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Ernest Rutherford
He discovered the nucleus. -
Ernest Rutherford
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Neils Bohr
He discovered the atomic nucleus. -
Neils Bohr
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James Chadwick
He discovered the neutron. -
James Chadwick
