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Events

Democritus

400 B.C

He claimed that matter was
made of small, hard particles
that he called “atomos”

John Dalton

1808

John Dalton created the very first atomic theory

J.J. Thomson

1897

electrons

Ernest Rutherford

1911

Rutherford discovered protons and the nucleus.

Niels Bohr

1913

Niels Bohr improved on Rutherford’s model.

James Chadwick

1932

Chadwick discovered neutrons.