Final answer:
Adding protons decreases the atomic radius while adding energy levels increases it.
Step-by-step explanation:
When protons are added to an atom, the positive charge of the nucleus increases. This stronger positive charge pulls the negatively charged electrons closer to the nucleus, resulting in a smaller atomic radius. This is because the attraction between the protons and electrons is stronger, causing the electrons to be held more tightly to the nucleus. On the other hand, adding energy levels (or shells) to an atom increases the atomic radius. As more energy levels are added, the outermost electrons are farther from the nucleus and experience weaker attraction.
Learn more about Effects of adding protons and energy levels on atomic radius