Why does atomic radius increase as you move down a group in the periodic table?

• A. Because electrons are removed from the atom, making it larger.
• B. Because the number of protons decreases, reducing the nuclear charge.
• C. Because additional electron shells are added, increasing the distance between the nucleus and the outermost electrons.
• D. Because the atoms gain more neutrons, which expand the electron cloud.

Answer: (C)

Verified step by step guidance

1. Understand that atomic radius refers to the average distance from the nucleus to the outermost electrons in an atom.
2. Recognize that as you move down a group in the periodic table, each element has an additional electron shell compared to the one above it.
3. Know that adding more electron shells increases the distance between the nucleus and the outermost electrons, which makes the atom larger.
4. Consider that although the nuclear charge (number of protons) increases down the group, the effect of added inner electron shells causes shielding, reducing the effective nuclear attraction on outer electrons.
5. Conclude that this shielding and increased distance due to more electron shells result in an increase in atomic radius as you move down a group.