Atomic Theory - Timeline

Niels Bohr finds that electrons travel in separate orbit bits around the nucleus

Henry Mosley used experiments to determine the atomic number of an element

De Brogile suggests that all matter has wave properties

Robert Millikan performs the oil drop experiment which discovers the charge of the electrons as negative

Proust discovers that a pure substance will always contain the same elements

John Dalton proposes the first atomic theory 1. All matter is made up of tiny invisible particles 2. Atoms of the same element are the same 3. Atoms of different elements are different 4. Atoms combine to form coumpunds

JJ Thompson discovers the electron and the first subtomic particle

Ernest Rutherford finds that the atom is mostly empty with a very tiny positive nucleus core

James Chadwick discovers the neutron