Which of the following best describes how atomic radius changes as you move down a group in the periodic table?

• A. Atomic radius remains constant because the number of valence electrons does not change.
• B. Atomic radius increases because additional electron shells are added.
• C. Atomic radius decreases due to stronger nuclear attraction.
• D. Atomic radius fluctuates unpredictably with no clear trend.

Answer: (B)

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. Recall 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. Recognize that adding more electron shells increases the size of the electron cloud, which generally increases the atomic radius.
4. Consider that although the nuclear charge increases down a group, the effect of added inner electron shells causes shielding, reducing the effective nuclear attraction on the outermost electrons.
5. Conclude that due to the addition of electron shells and shielding effect, the atomic radius increases as you move down a group in the periodic table.