Lewis Acid
Definition and meaning of Lewis Acid in chemistry.
A Lewis acid is any chemical species that is capable of accepting an electron pair from another species to form a coordinate covalent bond. This definition broadens the concept of acidity beyond the traditional requirement of hydrogen ion transfer.
In more detail
Proposed by the American chemist Gilbert N. Lewis in 1923, this theory identifies acids as electron-pair acceptors and bases as electron-pair donors. An atom, ion, or molecule with an incomplete octet or an empty orbital can successfully act as a Lewis acid. For example, transition metal cations are frequently Lewis acids because they have empty valence orbitals that can accommodate pairs of electrons from ligands. This theoretical framework is particularly useful for understanding reactions in non-aqueous solvents and the formation of complex coordination ions.
Key facts
| Field | General Chemistry |
|---|---|
| Core mechanism | Electron pair acceptance |
| Common types | Metal cations, molecules with incomplete octets |
In the reaction between boron trifluoride and ammonia, boron trifluoride acts as a Lewis acid by accepting a lone pair of electrons from the nitrogen atom of the ammonia molecule.
Frequently asked questions
Are all Bronsted-Lowry acids also Lewis acids?
Yes, a Bronsted-Lowry acid donates a proton, and that proton acts as a Lewis acid by accepting an electron pair. However, not all Lewis acids are Bronsted-Lowry acids.