Which of the following trends is observed as you move across a period from left to right on the periodic table?

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

Answer: (A)

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 (the net positive charge experienced by 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 increased nuclear charge affects other properties: ionization energy tends to increase (not decrease) because it requires more energy to remove an electron, and electronegativity also tends to increase as atoms more strongly attract electrons.
5. Metallic character decreases across a period because elements become less likely to lose electrons and more likely to gain or share electrons.