Repeating unit

In chemistry, a repeating unit or more properly constitutional repeating unit, is a small piece of a large molecule like a polymer or crystal that connects to itself over and over to build the bigger structure. The elements and chemical bonds in the repeating unit are responsible for the chemical and physical properties of the larger molecules.

By convention, polymers and ionic compounds are represented by their smallest repeating unit. One notable exception is polyethylene, which has a smallest repeating unit of  but is frequently represented by  which looks more like the repeating unit of the other vinyl polymers.

 References 

Category:Macromolecules