Physics 2000 Science Trek The Periodic Table

Evidence for Protons

Rutherford's experiment with the alpha particles convinced everyone that a small, positive nucleus existed inside every atom, but it wasn't clear what the nucleus was made of. Could nuclei be broken up into smaller pieces? Were all nuclei made of the same basic stuff, or were they different?

Rutherford, who was fond of alpha particles, tried shooting some at nitrogen gas. He set up a detector to track whatever came out; it detected some positively charged things that were neither alpha particles nor nitrogen nuclei. They had the same mass and charge as hydrogen nuclei. Rutherford concluded that each nitrogen nucleus contained hydrogen nuclei, knocked out by the alpha particles.

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