- The acid is the electron pair acceptor and can form a covalent bond with the electron pair donated by the base.
- The base is the electron pair donor.
In simple terms, a Lewis acid is a "electron-pair acceptor," while a Lewis base is an "electron-pair donor." The reaction between a Lewis acid and a Lewis base results in the formation of a coordinate covalent bond, in which both electrons in the bond come from the base.
Examples of Lewis Acids::
Protons (H+)
Metal ions (e.g., Fe3+, Al3+)
Electron-deficient molecules (e.g., BF3, SO3)
Lewis Acids
Examples of Lewis Bases::
Hydroxide ion (OH-)
Ammonia (NH3)
Water (H2O)
Alkenes (e.g., ethylene, propene)
General Reaction:
$$acid + base → adduct$$
$$Fe^{3+}(aq) + 6H_2O(l) → [Fe(H_2O)_6]^{3+}(aq)$$
In this reaction, Fe3+ acts as the Lewis acid, accepting electron pairs from the oxygen atoms of six H2O molecules, which function as Lewis bases. The product is a complex ion. $[Fe(H_2O)_6]^{3+}$.
Lewis acid-base reactions play a crucial role in various chemical and biological processes such as proton transfer reactions, metal complex formation, catalysis, and many important biochemical reactions in living organisms.
