Weegy: The nucleus contains: protons and nIn an isotope of an element the only difference between each isotope is the number of neutrons in the nucleus. [ The less neutrons the lighter the isotope, the more neutrons, the heavier the isotope.
In an ion the difference is the number of electrons in the outer valence shell of the atom. The more the atom has the more negative it is, the less the more positive it is. source: ] (More)