1. The Setup: Rutherford and his team bombarded a thin sheet of gold foil with alpha particles (positively charged particles). They expected the particles to pass through the foil with minimal deflection, as the prevailing "plum pudding" model of the atom suggested a diffuse, positively charged sphere with electrons embedded within.
2. The Unexpected Results: Much to their surprise, most of the alpha particles did pass straight through the foil, but some were deflected at large angles, and a very small number even bounced back towards the source.
3. The Interpretation: Rutherford realized that the only way to explain these results was if the positive charge of the atom was concentrated in a very small, dense region at the center, which he called the nucleus. This nucleus was responsible for deflecting the positively charged alpha particles.
4. The Conclusion: Since most of the alpha particles passed through the foil undisturbed, Rutherford concluded that the rest of the atom must be mostly empty space. This led to the development of the nuclear model of the atom, which proposed that the atom has a tiny, dense nucleus surrounded by a vast cloud of negatively charged electrons.
In essence, the fact that a small fraction of alpha particles were deflected at large angles, while the vast majority passed through, indicated that the atom was not a solid, uniform sphere, but had a small, dense region of concentrated positive charge surrounded by empty space.
