Question

why is a nucleus of an atom so dense?

Answer 1

electron cloud is VERY far away from the actual nucleus, and there is much space between the nucleus and the electron shell. So, the nucleus makes up very little of the atom's overall volume. However, electrons have a very, very, very small mass comapred to particles such as protons and neutrons (found in the nucleus) and therefore most of the mass is in the nucleus making it dense"