How does the atomic radius of elements change as you move from top to bottom within a chemical family (group) on the periodic table?

• A. The atomic radius increases.
• B. The atomic radius first increases, then decreases.
• C. The atomic radius decreases.
• D. The atomic radius remains the same.

Answer: (A)

Verified step by step guidance

1. Understand that the atomic radius is the average distance from the nucleus to the outermost electrons in an atom.
2. Recognize that as you move down a group (family) in the periodic table, each successive element has an additional electron shell (energy level) compared to the one above it.
3. Know that adding more electron shells increases the distance between the nucleus and the outermost electrons, which tends to increase the atomic radius.
4. Consider that although the nuclear charge (number of protons) also increases down the group, the effect of added electron shells (shielding effect) outweighs the increased nuclear charge, resulting in a larger atomic radius.
5. Conclude that the atomic radius increases as you move from top to bottom within a chemical family (group) on the periodic table.