How do the electronegativities of elements generally change as you move from left to right across a period and from top to bottom down a group in the periodic table?

• A. Electronegativity increases across a period and decreases down a group.
• B. Electronegativity decreases across a period and increases down a group.
• C. Electronegativity remains constant across a period and down a group.
• D. Electronegativity decreases both across a period and down a group.

Answer: (A)

Verified step by step guidance

1. Understand that electronegativity is a measure of an atom's ability to attract and hold onto electrons in a chemical bond.
2. Recall 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 effective nuclear charge experienced by the valence electrons.
3. Because of the increased effective nuclear charge across a period, atoms more strongly attract electrons, so electronegativity generally increases from left to right across a period.
4. As you move down a group in the periodic table, additional electron shells are added, increasing the distance between the nucleus and the valence electrons and causing more electron shielding.
5. This increased distance and shielding reduce the nucleus's pull on valence electrons, so electronegativity generally decreases as you move down a group.