What type of reaction occurs when alkenes are used to form polymers such as poly(ethene)?

The reaction is called addition polymerisation, where many alkene monomers join together to form a large polymer chain.

This answer demonstrates understanding of the process of addition polymerisation, which is a key concept in organic chemistry related to alkenes. It tests the student's ability to connect the structure of alkenes to their chemical reactions. This response is aligned to Polymerisation and naturally occurring polymers because it explains alkenes can be used to make polymers such as poly(ethene) and poly(propene) by addition polymerisation using the correct AQA GCSE Chemistry organic context. Keep molecular formula, structural formula, displayed formula, and general formula distinct. Do not confuse alkanes with alkenes, saturated with unsaturated, cracking with combustion, polymers with monomers, or hydrocarbons with oxygen-containing alcohols and carboxylic acids. When formulae are used, preserve the stored notation exactly and explain the GCSE chemistry idea in words rather than using unsupported displayed-formula diagrams.