As you move from left to right across a period in the periodic table, how does the atomic radius of the elements generally change?

• A. It first increases, then decreases.
• B. It increases.
• C. It decreases.
• D. It remains constant.

Answer: (C)

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. Recognize that as you move from left to right across a period in the periodic table, the number of protons in the nucleus increases, which increases the positive charge (nuclear charge).
3. Note that the electrons are added to the same principal energy level (same shell), so the shielding effect remains relatively constant.
4. Because the increased nuclear charge pulls the electrons closer to the nucleus without much increase in shielding, the atomic radius decreases across the period.
5. Therefore, the general trend is that atomic radius decreases as you move from left to right across a period.