Scattering of a-particles by a thin gold foil suggests the presence of

The scattering of alpha particles by a thin gold foil, conducted by Ernest Rutherford, Geiger, and Marsden, suggested the presence of a small, dense, and positively charged nucleus at the center of the atom. During the experiment, most alpha particles passed through the foil, indicating that atoms are mostly empty space. However, some particles were deflected at large angles, and a few even bounced backward. This observation contradicted the then-prevalent 'plum pudding' model, which assumed positive charge was uniformly distributed. Rutherford concluded that such significant deflection could only occur if the atom's positive charge and most of its mass were concentrated in a very small central region, which he named the nucleus. This discovery fundamentally shifted the atomic model from a diffuse sphere to a nuclear structure.

Sources

1. [1] https://www.britannica.com/science/Rutherford-model