Final answer:
Cations are smaller than parent atoms, while anions are larger.
Step-by-step explanation:
The sizes of cations and anions are compared to their parent atoms.
In general, a cation is smaller in size than its parent neutral atom. This is because the cation has lost one or more electrons, resulting in a decrease in electron-electron repulsion and an increase in effective nuclear charge.
An anion, on the other hand, is larger than its parent neutral atom. This is because the anion has gained one or more electrons, resulting in an increase in electron-electron repulsion and a decrease in effective nuclear charge.