Alpha scattering
The deflection of alpha particles (helium-4 nuclei) by atomic nuclei, studied experimentally by Rutherford. Rutherford scattering provides evidence for the nuclear model: the nucleus is small, dense, and positively charged. The scattering angle depends on impact parameter (closest approach distance).
Real World
In 1909, Geiger and Marsden at the University of Manchester fired alpha particles at gold foil and found roughly 1 in 8,000 bounced back — the result that led Rutherford to propose the nuclear model of the atom.
Exam Focus
When asked to 'explain' Rutherford's results, explicitly link each observation (most pass through / some deflect / rare backscatter) to a specific property of the nucleus.
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