How was the plum pudding model disapproved?

Answer 1

Imagine firing a gun at a plum pudding. You would be extremely surprised if the bullet bounced back.

Rutherford directed a beam of alpha particles at gold foil. While the majority went through, a number were detected coming back towards the alpha source.

If the protons and electrons in an atom were like a plum pudding no alpha particles would come back.

If they were like ball bearings filling the entire atom none would get through

However, most went through and a few bounced back, demonstrating that the positive charge was concentrated in a small nucleus. The numbers being deflected back or at various other angles agreed with inverse square repulsion between the alpha particle and the nucleus, showing that the alpha particles never actually hit the nucleus, and thus the maximum size of the nucleus could be determined (about 1/10000 of the diameter of the atom)

Answer 2

Plum Pudding model for the atom was proposed by J. J. Thompson. It states that electrons are located among protons, hence hard material with no spaces. Rutherford's alpha particle experiment proved that almost entire space of an atom is vacant.

Answer 3

The Thomson model doesn't explain the electron shells and movement of electrons.

Answer 4

The atomic nucleus was not discovered yet.