Rutherford investigated atoms by firing small, positively charged particles at a thin sheet of gold foil. What results would he expect to see if he believed Thomson’s model of the atom to be correct?
If Thomson’s model of the atom were correct, Rutherford should have seen a complete reflection of those particles when fired at the foil. Those particles would have hit a solid object (Thomson model) and would have been reflected back at the emitter. However, Rutherford discovered that most of those particles passed through the sheet, either continuing straight through or having the angle change a small amount (bouncing off the nucleus). Only a small number of the particles were reflected back, having hit the nucleus straight on. This led him to believe that there was a small, dense portion of the atom that resided within a larger, emptier space.
