How can I identify a Lewis base?

1 Answer
Dec 4, 2014

You draw the Lewis structure and look for a pair of electrons that can form a bond to another atom.

A Lewis base is a molecule or ion that can donate a pair of electrons to form a bond.

An atom, ion, or molecule with a lone-pair of electrons can be a Lewis base.

Each of the following can "give up" their electrons to something that will accept them:

HO:⁻, :N≡C:⁻, CH₃COO:⁻, :NH₃, H₂O:, and :C≡O:

In the above example, the ammonia is the Lewis base because it donates its lone pair of electrons to H⁺ to form a bond.

In organic chemistry, many compounds with π electrons act as Lewis bases.

The alkene above is a Lewis base, because it donates its π electrons to form a bond to the H⁺.

Here’s a video on identifying Lewis bases and acids.