Conjugate Acid and Base

[805132275]

Does the concept of conjugate acids and bases only apply to Lewis acid and bases or is it inclusive to bronsted acid and bases?

[armintaheri]

I think you have that backwards. The concept of conjugates exists in Bronsted-Lowry, since it deals with proton exchange. An acid loses a proton and becomes its conjugate base, a base gains a proton becomes its conjugate acid. Lewis acids and bases don't always exchange protons. For example, BF₃ is a Lewis acid. It can accept an electron pair from F^-, which is a Lewis base, and become BF₄^-. Since there are no protons being gained or lost, the concept of conjugates makes no sense here. It only applies to Lewis acids and bases if they are also Bronsted-Lowry acids and bases, like NH₃ and NH₄⁺.