Question

What did Rutherford discover that Thomson did not understand?

Answer 1

That most of an atom's mass was packed in the central nucleus.

Step-by-step explanation:

Rutherford disproved Thomson's model in 1911 with his gold foil experiment, in which he demonstrated that the atom has a high-mass nucleus.

Answer 2

Answer: That most of an atom's mass was packed in a central nucleus