Poly(ethene) is a polymer made from very many ethene molecules combined together.
The reaction is called a polymerisation reaction:
The C=C double bond in ethene is involved in the polymerisation reaction. It allows ethene molecules to join together to form a single product, so it is an example of an addition reaction. Poly(ethene) is an addition polymer.
It is too difficult to model a complete addition polymer molecule, as it contains many atoms. Instead, we show the structure of its repeating unit, the part that is repeated many times. To deduce the structure of a polymer from the monomer:
The table shows the structure of ethene and its polymer.
Equations use repeating units to model addition polymerisation reactions. The letter n stands for a large number. In general:
n(monomer) → [repeat unit]n
The diagram shows the structure of propene. Deduce the structure of poly(propene), and use this to show an equation for the polymerisation of propene.