How does the atomic radius of elements change as you move from left to right across a period in the periodic table?

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

Answer: (B)

Verified step by step guidance

1. Understand that the atomic radius is the distance from the nucleus of an atom to the outermost electrons.
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 nuclear charge.
3. Know that the increased nuclear charge pulls the electrons closer to the nucleus, reducing the size of the electron cloud.
4. Note that although electrons are added across the period, they are added to the same principal energy level, so the shielding effect does not increase significantly.
5. Conclude that because of the stronger attraction between the nucleus and electrons, the atomic radius decreases as you move from left to right across a period.