Here's how it worked:
1. Alpha particles: Rutherford used a radioactive source that emitted alpha particles, which are positively charged helium nuclei.
2. Gold foil: These alpha particles were then directed at a thin sheet of gold foil.
3. Interaction: Most alpha particles passed straight through the gold foil, as expected if atoms were mostly empty space. However, some alpha particles were deflected at different angles.
4. Fluorescent screen: The fluorescent screen was coated with a material that emitted light when struck by alpha particles. By observing the pattern of light flashes on the screen, Rutherford could deduce the paths of the deflected alpha particles.
Key Observation: The surprising observation was that a small percentage of alpha particles were deflected at very large angles, some even bouncing back towards the source. This led Rutherford to conclude that:
* Atoms have a tiny, dense, positively charged nucleus at their center: The alpha particles that were deflected at large angles must have collided with this nucleus.
* Most of the atom is empty space: The fact that most alpha particles passed straight through the foil indicated that most of the atom's volume is empty space.
In summary, the fluorescent screen allowed Rutherford to visually track the paths of alpha particles and observe their unexpected deflections, ultimately leading to his groundbreaking discovery of the atomic nucleus.
