Which statement correctly defines a Lewis base?

Which statement correctly defines a Lewis base?

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

Answer: (B)

A Lewis base is a species that donates an electron pair to a Lewis acid, increasing the electron density at the atom that accepts the pair. This donation forms a bond, often a coordinate covalent bond, between the base and acid. For example, ammonia has a lone pair on nitrogen that can be donated to an electron-poor boron atom in boron trifluoride, creating a Lewis acid–base adduct. This contrasts with donating H+ ions, which is a Brønsted–Lowry acid behavior rather than a Lewis base behavior; accepting electrons describes a Lewis acid; and accepting OH− isn’t the defining action of a Lewis base. The key idea is electron-pair donation to an electron-paiting center.

A Lewis base is a species that donates an electron pair to a Lewis acid, increasing the electron density at the atom that accepts the pair. This donation forms a bond, often a coordinate covalent bond, between the base and acid. For example, ammonia has a lone pair on nitrogen that can be donated to an electron-poor boron atom in boron trifluoride, creating a Lewis acid–base adduct. This contrasts with donating H+ ions, which is a Brønsted–Lowry acid behavior rather than a Lewis base behavior; accepting electrons describes a Lewis acid; and accepting OH− isn’t the defining action of a Lewis base. The key idea is electron-pair donation to an electron-paiting center.