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

• A. Because atoms lose protons as you move down a group, reducing the attraction to electrons.
• B. Because electrons are removed from the outer shell, making the atom larger.
• C. Because additional electron shells are added, increasing the distance between the nucleus and the outermost electrons.
• D. Because the effective nuclear charge decreases significantly, pulling electrons closer to the nucleus.

Answer: (C)

Verified step by step guidance

1. Understand that atomic radius refers to the size of an atom, typically measured from the nucleus to the outer boundary of the electron cloud.
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 naturally increases the atomic radius.
4. Consider that although the number of protons (nuclear charge) increases down a group, the effect of this increased positive charge is partially offset by the shielding effect of the inner electron shells, which reduces the effective nuclear attraction felt by the outermost electrons.
5. Conclude that the dominant factor causing the increase in atomic radius down a group is the addition of electron shells, which outweighs the increase in nuclear charge and results in a larger atomic size.