jan 1, 1911 - Geiger, Marsden, and Rutherford discovered the nucleus in 1911
following experiments to test the 'Plum Pudding' model. They
fired beams of alpha particles at a thin piece of gold foil,
expecting them to pass through. Many did, but some alpha
particles were deflected and others bounced straight back.
This, they discovered, was because the positively charged nucleus
was in the way.
Added to timeline:
Developement of Ideas About the Atom
Date:
