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

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

Answer: (A)

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 (energy level) 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 shielding, where inner electrons reduce the effective nuclear charge felt by outer electrons, allowing the outer electrons to be held less tightly and thus increasing the atomic size.
5. Conclude that because of the addition of electron shells and increased shielding, the atomic radius increases as you move down a group in the periodic table.