Here's why:
* Alpha particles: These are positively charged particles, relatively massive compared to electrons.
* Gold foil: A thin sheet of gold was used as a target.
* Expected outcome: Based on the prevailing "plum pudding" model of the atom (electrons embedded in a positively charged sphere), most alpha particles were expected to pass straight through the foil with minor deflections.
* Actual outcome: While many alpha particles did pass straight through, a significant number were deflected at large angles, and some even bounced back.
This surprising result led Rutherford to propose the nuclear model of the atom:
* Nucleus: A tiny, dense, positively charged core at the center of the atom.
* Electrons: Negatively charged particles orbiting the nucleus in a vast, mostly empty space.
The deflection of alpha particles was explained by their interaction with the positively charged nucleus. The vast majority of an atom's volume is empty because the electrons occupy a much larger space compared to the nucleus.
