sep 20, 1932 - Discovery of the Neutron

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James Chadwick discovered the neutron. He announced a new uncharged particle. It was discovered last because there is no charge so there would be no electrical repulsion or way to see a charge so it was deemed neutral or a neutron. He was originally assigned the task of tracking down evidence for Rutherford's tightly bound proton and electron pair but instead found proof of a neutron.

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