What contribution is a modification to thomson plum pudding model

Thomson's "Plum Pudding" model of the atom was the first to show electrons as discrete charged particles. However, it didn't account for any separation of charges, and it assumed that atoms have a homogeneous mass distribution. Rutherford's gold foil experiment showed that there would have to be some sort of dense, positively-charged nucleus, so further models of the atom after that moved the negatively-charged electrons out to "orbitals," a term that is still in use today, while keeping the positive charge in a discrete and dense nucleus.