Which of the following best explains why electronegativity increases across a period in the periodic table?

• A. The number of energy levels increases, allowing more electrons to be attracted.
• B. The number of protons in the nucleus increases, resulting in a stronger attraction for bonding electrons.
• C. The shielding effect increases, enhancing the ability to attract electrons.
• D. The atomic radius increases, making it easier for atoms to attract electrons.

Answer: (B)

Verified step by step guidance

1. Understand that electronegativity is the ability of an atom to attract bonding electrons toward itself in a chemical bond.
2. Recognize that as you move across a period in the periodic table, the number of protons in the nucleus increases, which increases the positive charge of the nucleus.
3. Note that the number of energy levels (electron shells) remains the same across a period, so the shielding effect does not significantly increase.
4. Realize that the increased positive charge pulls the electrons closer, decreasing the atomic radius and increasing the nucleus's pull on bonding electrons.
5. Conclude that the increase in nuclear charge without a significant increase in shielding causes electronegativity to increase across a period.