Plastics

:Alkenes are reactive and so are useful for making many other substances including polymers.

Polymers have very large molecules. They are formed when many small molecules join together. This process is called polymerisation.

 When alkenes join together to form a polymer with no other substance being produced in the reaction, the process is called addition polymerisation.

Plastics are polymers and are made by polymerisation.

Example: poly(ethene) (often called polythene) is made by polymerising the simplest alkene, ethene.