Why do stable nuclei never have more protons than neutrons?
Hint: The stability of a nucleus depends on the forces between the nucleons.
Step 1: Interpret the forces between the nucleons.
Becaus protons are positively charged and repel one another electrically.
This repulsion becomes so great in nuclei with more than 10 protons or so, that an excess of neutrons which produce only attractive forces, is required for stability.
