Urea, a compound formed in the liver, is one of the ways humans excrete nitrogen. The Lewis structure for urea is H N H H C H O N Using hybrid orbitals for carbon, nitrogen, and oxygen, determine which orbitals overlap to form the various bonds in urea is:

The nitrogens are both sp3 hybridized. Their bonds are formed by sp overlaps. The carbon and oxygen are sp2 hybridized. The double bond with oxygen is produced by a sp2 overlap to form the sigma component and a probital overlap to form the pi component. The bonds with hydrogen are formed by sp2 overlaps.