Addition Polymerisation – From Monomers to Polymers Explore how small alkene molecules join together to form long-chain polymers through addition polymerisation. Select different monomers, watch their carbon–carbon double bonds open to form new covalent bonds, and investigate how repeating units are represented using correct chemical notation. Discover why polymers are solids at room temperature by exploring strong covalent bonds within polymer chains and intermolecular forces between them. Compare the structures of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) to understand how branching affects packing, density and melting behaviour. Interactive animations, exam-style diagrams and knowledge-check questions help GCSE Chemistry students visualise polymer formation and explain the relationship between structure, bonding and properties. simopsis