Which observations helped Rutherford determine that atoms have tiny dense positively charged nuclei?

A+ answer: A few of the alpha particles in his expeirment were deflected from the gold foil at large angles.

Scattering pattern of alpha particles 'shot' at a thin gold foil. Most went straight thru showing the nucleus was very small. Analysis of the scattering showed electrical repulsion, not that the particles actually hit the nucleus and bounced off.