As we move down a group in the periodic table, how does the atomic radius of the elements change?

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

Answer: (B)

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. 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 distance between the nucleus and the outermost electrons, which tends to increase the atomic radius.
4. Consider the effect of increased nuclear charge (more protons) as you move down the group, but note that the shielding effect from inner electrons reduces the effective nuclear attraction on the outermost electrons.
5. Conclude that because the shielding effect outweighs the increased nuclear charge, the atomic radius increases as you move down a group in the periodic table.