What is polymer? Explain in detail.

The macromolecules which are formed by combination of one or more than two types of simple molecules by chemical bond formation are called polymers. The process of one or more than two types of simple molecules that combine by chemical bond formation is called polymerisation. Polythene is formed by addition reaction of molecules of ethene with one another. In this reaction, two molecules of monomer ethene combine in the first step and form a dimer. And when third molecule combines with dimer and forms a trimer. A trimer combines with fourth monomer and forms a tetramer. In the same way a long chain is formed which is called polymer.