Lewis Base
Definition and meaning of Lewis Base in chemistry.
A Lewis base is any chemical species that can donate a pair of nonbonding electrons to another species to form a coordinate covalent bond. This definition broadens the concept of a base beyond just the donation of hydroxide ions or the acceptance of protons.
In more detail
Proposed by Gilbert N. Lewis, this theory focuses on electron transfer rather than proton transfer. For a molecule or ion to act as a Lewis base, it must have at least one lone pair of electrons available for donation. When a Lewis base donates this electron pair to an electron-deficient species, which is known as a Lewis acid, they form a Lewis acid-base adduct. This concept is incredibly powerful because it explains many reactions in coordination chemistry, such as the binding of ligands to transition metal ions, which cannot be explained by the traditional Brønsted-Lowry theory.
Key facts
| Field | General Chemistry |
|---|---|
| Key Action | Donates an electron pair |
| Requirement | Must have a lone pair |
Ammonia (NH3) acts as a Lewis base when its nitrogen atom donates its lone pair of electrons to boron trifluoride (BF3), forming a stable adduct.
Frequently asked questions
Can a molecule be a Lewis base without being a Brønsted-Lowry base?
Yes, many molecules, like carbon monoxide, can donate an electron pair to a metal center without having any tendency to accept a proton.