Monomer

Each small starting molecule is a monomer; the very large molecule formed when many monomers join is a polymer. In addition polymerisation, the carbon–carbon double bond in each monomer becomes a single bond, and new covalent bonds connect the monomers into a chain.

Each large molecule is built by joining many smaller molecules called monomers. The prefix poly- means “many”, so a polymer contains many monomer units joined together.

Small molecules called monomers can join together to produce these chains; the recurring section of the finished chain is its repeating unit.

A monomer is a small molecule able to join to other monomer molecules. During polymerisation, very many monomers become connected by covalent bonds, producing a long-chain molecule called a polymer. Because a polymer molecule contains so many atoms, it has a high average relative molecular mass.