Which statement describes Lewis acid?

Which statement describes Lewis acid?

• A. A substance that donates electrons
• B. A substance that donates H+ ions
• C. A substance that accepts H+ ions
• D. A substance that accepts electrons

Answer: (D)

In Lewis acid-base theory, an acid is defined by its ability to accept an electron pair. That makes the statement describing a substance that accepts electrons the correct one. For example, BF3 accepts a lone pair from NH3, forming a Lewis acid–base adduct. The other descriptions align with different concepts: donating electrons describes a Lewis base, donating H+ aligns with Brønsted–Lowry acids, and accepting H+ aligns with Brønsted–Lowry bases. The Lewis framework centers on electron-pair transfer, not proton transfer, which is why accepting electrons identifies a Lewis acid.

In Lewis acid-base theory, an acid is defined by its ability to accept an electron pair. That makes the statement describing a substance that accepts electrons the correct one. For example, BF3 accepts a lone pair from NH3, forming a Lewis acid–base adduct. The other descriptions align with different concepts: donating electrons describes a Lewis base, donating H+ aligns with Brønsted–Lowry acids, and accepting H+ aligns with Brønsted–Lowry bases. The Lewis framework centers on electron-pair transfer, not proton transfer, which is why accepting electrons identifies a Lewis acid.