Illustrated Glossary of Organic Chemistry

Trivalent: An atom having three covalent bonds.

In this molecule the hydrogen atom and chlorine atoms are monovalent, the oxygen atom is divalent, the nitrogen atom is trivalent, and the carbon atom is tetravalent.

This molecule contains three trivalent nitrogen atoms. The nitrogen atom of the amino group has three single bonds. The nitrogen atom of the imine group has one single bond and one double bond. The nitrogen atom of the nitrile group has one triple bond.