Anions typically act like which type of species?

Anions typically act like which type of species?

• A. Arrhenius bases
• B. Bronsted-Lowry acids
• C. Lewis acids
• D. Lewis bases

Answer: (D)

Anions act as Lewis bases because, in Lewis acid–base theory, a base is defined as an electron-pair donor. Anions have extra electrons or a negative charge, giving them available electron density that they can share with an electron-deficient species (a Lewis acid). When an anion donates this electron pair to a Lewis acid, it forms a bond or coordinates to the center, which is exactly the behavior of a Lewis base. This perspective is broader than Arrhenius bases, which require OH− production in water, and than Bronsted-Lowry acids, which donate protons; while some anions can participate in those roles, their typical and most general behavior is as electron-pair donors, i.e., Lewis bases.

Anions act as Lewis bases because, in Lewis acid–base theory, a base is defined as an electron-pair donor. Anions have extra electrons or a negative charge, giving them available electron density that they can share with an electron-deficient species (a Lewis acid). When an anion donates this electron pair to a Lewis acid, it forms a bond or coordinates to the center, which is exactly the behavior of a Lewis base. This perspective is broader than Arrhenius bases, which require OH− production in water, and than Bronsted-Lowry acids, which donate protons; while some anions can participate in those roles, their typical and most general behavior is as electron-pair donors, i.e., Lewis bases.