* The atom has a dense, positively charged nucleus at its center. The alpha particles, which are also positively charged, were repelled by this nucleus.
* The nucleus is very small compared to the overall size of the atom. Most alpha particles passed through the foil without any significant deflection, indicating that most of the atom's space is empty.
* The mass of the atom is concentrated in the nucleus. The large deflection of a few alpha particles indicated that they had encountered a massive, positively charged entity, which he concluded was the nucleus.
In essence, Rutherford's interpretation of the small number of particles bouncing back was a revolutionary shift in the understanding of atomic structure. It contradicted the then prevailing "plum pudding model" of the atom, which envisioned a diffuse, positively charged sphere with electrons scattered throughout.
