As you move across a period from left to right on the periodic table, which of the following trends is observed?

• A. Ionization energy decreases
• B. Atomic radius decreases
• C. Metallic character increases
• D. Electronegativity decreases

Answer: (B)

Verified step by step guidance

1. Understand that moving across a period from left to right means moving from elements with fewer protons to elements with more protons in the same energy level.
2. Recall that as the number of protons increases, the effective nuclear charge experienced by the electrons also increases, pulling the electron cloud closer to the nucleus.
3. Recognize that this stronger attraction causes the atomic radius to decrease because the electrons are held more tightly and the size of the atom shrinks.
4. Consider how this trend affects other properties: ionization energy generally increases (not decreases) because electrons are held more tightly, metallic character decreases, and electronegativity increases.
5. Conclude that the correct trend observed across a period from left to right is that the atomic radius decreases.