Elaborate on how the nuclear model of the atom is an improvement on previous models

In previous Plums Pudding atomic model,  atom is spherical particle with a positive charge dotted with negatively charged electrons both around and inside it. Later proposed nuclear model is an improvement, which describes the electrons stay in orbit with distinct energy level. Nucleus made up of neutral particles (neutrons) and postively charged particles (protons). Nucleus is surrounded by electrons. Electron can be gained and lost by an atom. Nucleus is much smaller than the size of the atom and nucleus exist in cneter of an atom. Nuclear model explains the isotopes of an atom as well.

The number of protons in a nucleus