Describe the distribution of mass within an atom

The nuclei of most atoms also contain neutrons . The masses of subatomic particles are very tiny. ... Since the nucleus contains protons and neutrons, most of the mass of an atom is concentrated in its nucleus. Protons and electrons have electrical charges that are equal and opposite.

There are 2 places where charge is located in the atom:

the nucleus contains neutrons (zero charge) and protons (positive charge)

Around the nucleus there are electrons located on electron shields and the charge of electrons is equal to the charge of protons in the nucleus, but have negative sign.

To sum it all up we can say that the charge of protons in the nucleus is reduced by the charge of electrons on the orbits to make the atom electrically neutral.