The chemical formula for urea is CO(NH2)2. When written in formula format, it shows the carbon atom "C" is joined to the oxygen atom by a double ionic bond, and the two ammonium molecules "NH2" are bound by single bonds to the carbon atom.
The double-bonded carbon and oxygen atoms form a carbonyl group and leave two electrons free on the carbon atom for the ammonium groups to attach.
Urea, also known as carbamide, occurs in nature as the primary end product of protein metabolism. Measurement of blood urea nitrogen is a critical indicator of renal function. Synthesized urea in 1828 was the first organic compound to be made from inorganic or nonliving materials.