Final answer:
The atomic radius generally decreases along each period and increases down each group in the periodic table.
Step-by-step explanation:
The atomic radius is an indication of the size of an atom. The trend for atomic radius is that it generally decreases along each period (row) of the periodic table and increases down each group (column). This means that as you move across a period from left to right, the atomic radius gets smaller, and as you move down a group from top to bottom, the atomic radius gets larger. For example, from potassium (K) to krypton (Kr) within the same period, the atomic radius decreases, while within the alkali metals group, such as lithium (Li) or sodium (Na), the atomic radius increases as you move down the group.