Polymers are very large molecules made by joining many small molecules together. The small molecules are called monomers. Poly(ethene) is made from the monomer ethene, C2H4.
In a polymer the atoms are joined in long chains. In poly(ethene) each molecule is a very long chain of carbon atoms, with hydrogen atoms attached to the carbon atoms. All the atoms in a chain are held together by strong covalent bonds.
Poly(ethene) is a simple polymer. The forces between separate chains are weak intermolecular forces, so the chains can be pulled past each other and poly(ethene) is flexible. These weak forces are easily overcome when it is heated, so it has a fairly low melting point. It does not conduct electricity because it has no free electrons or ions.
