When Ernest Rutherford discovered the nucleus of the atom?
The proton, if you had to give a name to it, was discovered by Rutherford. The neutron was later identified by Chadwick. Rutherford determined through his gold foil experiment that there was indeed a small, dense, positive nucleus. The problem he was unable to answer is from where did all the extra mass come from. That question was later answered by Chadwick. Rutherford did not discover the proton so to speak, but he did discover a positive center of the atom. Everybody added something else to the atomic models as they went along, and our understanding of the atom got better. Nobody’s model was ever perfect. Another shortcoming of Rutherford’s model is that he could not explain why the electrons did not crash into the nucleus. That was answered later by Neils Bohr.
