1. Starter 1.What does the word ‘synthetic’ mean? 2.What does the word ‘biodegradable’ mean? 3.Give 2 advantages of synthetic materials over natural materials.

2. Monomers and Polymers Aim of lesson: To understand how plastics are formed from crude oil

3. Plastics are Polymers A polymer is a very big molecule made from many small molecules (called monomers). The process in which the monomers join to make a polymer is called polymerisation. Monomer Polymer Mono= onePoly= many Polymerisation

4. Structure of Monomers Many plastics or polymers are made from unsaturated monomers obtained by cracking. The simplest monomer is ethene, C 2 H 4 Ethene monomers join together to give a polymer called poly(ethene), which is often called polythene.

5. Polymerisation of Ethene 4 monomer units have joined together to form the polymer

6. How do monomers join to make a polymer? 1. A chemical is added which breaks the double bond between the two carbon atoms of ethene to make a very reactive unit. Ethene monomer Reactive unit (Repeating unit)

7. 2. Reactive units join together, end to end and a big molecule or polymer is made. Reactive units (Repeating units) + Start of polymer

8. The process is called addition polymerisation because the monomer units join together to give one product, by a series of reactions in which the double bond breaks. Addition Polymerisation

9. Repeating Units This is a group of atoms in the polymer structure which is repeated over and over again. If you are asked to draw the repeating unit from a polymer you must always show bonds at either end of the unit e.g. is the repeating unit for 4 repeating units shown here

10. Many plastics are made from alkenes, or from unsaturated molecules made from alkenes. Modern Name of Monomer Original Name of Monomer Modern Polymer Name Original Polymer Name Ethene Poly(ethene)Polythene Chloroethene Vinyl chloride Poly(chloroethene) Polyvinyl chloride (P.V.C.) Propene Poly(propene)Polypropene PhenyletheneStyrenePoly(phenylethene)Polystyrene Naming Plastics