Which term describes the small molecule that repeats to form a polymer?

• A. Monomer
• B. Dimer
• C. Oligomer
• D. Polymer

Answer: (A)

The main idea is that polymers are built from small starting units called monomers. A monomer is a single molecule that can join with others to form a long chain. For example, ethene is the monomer that can link together to make polyethene; each repeating unit in the polymer comes from one monomer. A dimer would be just two molecules linked together, not the repeating unit of the whole chain. An oligomer is a short polymer with only a few repeating units, while a polymer has many. So the small molecule that repeats to form the polymer is the monomer.