Rutherford’s alpha particle scattering experiment led to the discovery of the atomic nucleus.
Elaboration:
Rutherford’s experiment, where alpha particles (helium nuclei) were directed at a thin gold foil, showed that most of the positively charged particles were deflected or bounced back, indicating a concentrated positive charge at the center of the atom, which he named the nucleus.
This discovery contradicted the existing “plum pudding” model of the atom, which suggested that the positive charge was evenly distributed throughout the atom.
The experiment demonstrated that the atom is mostly empty space, with a tiny, dense, positively charged nucleus at the center.