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

• A. Because additional electron shells are added, increasing the distance between the nucleus and the outermost electrons.
• B. Because atoms gain more protons, which decreases the size of the atom.
• C. Because electrons are removed from the outer shell, causing the atom to expand.
• D. Because the effective nuclear charge increases significantly, pulling electrons closer to the nucleus.

Answer: (A)

Verified step by step guidance

1. Understand that atomic radius refers to the size of an atom, typically measured as the distance from the nucleus to the outermost electron shell.
2. Recognize that as you move down a group in the periodic table, each successive 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 generally causes the atomic radius to increase.
4. Consider that although the number of protons (nuclear charge) also increases down a group, the effect of added inner electron shells (which shield outer electrons) reduces the effective nuclear charge felt by the outermost electrons.
5. Conclude that the increased shielding and added shells outweigh the increased nuclear charge, resulting in a larger atomic radius as you move down a group.