Niels Bohr arranged electrons, J.J. Thomson discovered them, John Dalton proposed modern atomic theory based on ratios, and Ernest Rutherford found the positive charge in atoms.
Niels Bohr: Contribution - The arrangement of electrons around the nucleus in energy levels
J.J. Thomson: Contribution - Discovery of electrons
John Dalton: Contribution - Postulated modern atomic theory based on fixed ratios of elements
Ernest Rutherford: Contribution - Discovery that positive charge is concentrated in the center of the atom
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