Bronsted and Lewis acids/base

[Qinyan Feng 1H]

Hi

I remember Dr. Lavelle said something like "bronsted acids are always lewis acids", (or something in reverse, I cannot remember). Could someone help me to clarify this point and explain why?

Thank you.

[AudreyQian1J]

Hello,
Yes, Bronsted acids are Lewis acids in the sense that the Lewis theory is more general than the Bronsted-Lowry theory. A Lewis acid accepts an electron pair, whereas a Bronsted acid donates a proton. In the same sense that a Bronsted acid is a proton donor, a proton acts as a Lewis acid when it attaches to a lone pair provided by a Lewis base.

[Devika Nair 2D]

Lewis acids are any atoms/molecules that accept electron pairs. Bronsted acids accept electron pairs to replace a hydrogen (hydrogen ion donor). Lewis acids are more general, Bronsted acids are more specific. All Bronsted acids are Lewis acids, but not all Lewis acids are Bronsted acids.

[Sophie Vikram 1L]

Lewis acids and bases are a more general definition of acids and bases. The lewis acid and base idea states that all electron donors are bases and acids accept these donated electrons. In a sense, electron donors/bases act somewhat as cations, and electron acceptors/acids act as anions. This is a very general idea; the bronsted-lowry idea of an acid and base involves the donation and acceptance of electrons/"protons" using the idea of hydrogen protons. Thus, it is more specific but still falls under the lewis acid and base categorization.

ALL bronsted acids/bases are lewis acids/bases but NOT ALL lewis acids/bases are bronsted acids/bases.

[Caitlin Gee 2K]

You're correct because the Lewis theory has a more broad definition for acid, so it encompasses the definition of Bronsted acids. This means that all Bronsted acids are Lewis acids.

[Isabelle Rieke-Wey 2G]

Hi!
This is true, because Lewis theory encompasses Bronsted acids as it has a more general/broad definition of acids. As a result, all bronsted acids are Lewis acids, but not the other way around.