Why does electronegativity decrease from right to left within a period on the periodic table?

• A. Because atomic radius decreases, making it easier for atoms to attract electrons.
• B. Because atoms gain more electrons, increasing their tendency to attract additional electrons.
• C. Because the number of energy levels increases, increasing the shielding effect.
• D. Because the number of protons decreases, resulting in a weaker attraction for bonding electrons.

Answer: (D)

Verified step by step guidance

1. Understand that electronegativity is the measure of an atom's ability to attract and hold onto electrons in a chemical bond.
2. Recognize that within a period (row) of the periodic table, atoms have the same number of energy levels (shells), so shielding effect remains relatively constant.
3. Note that as you move from right to left across a period, the number of protons in the nucleus decreases, which reduces the positive nuclear charge.
4. With fewer protons, the nucleus exerts a weaker attractive force on the bonding electrons, causing electronegativity to decrease.
5. Therefore, the decrease in electronegativity from right to left is primarily due to the decreasing nuclear charge, not changes in atomic radius or shielding.