Answer:
Ernest Rutherford
Step-by-step explanation:
Atomic nuclei were discovered in 1911 by scientist Ernest Rutherford. He was also responsible for an important observation: the center (nucleus) of atoms contains protons. The neutron was identified years later by other scientists.
The nucleus is definitely very small compared to the size of the atom. To get an idea of its tiny size, let's compare the atom as if it were a football stadium, so the nucleus would be about the size of a pea.