Question

Why is plastic known as polymer?

Answer 1

Hint: Consider the similarities between plastics and polymers. These similarities relate to structural similarities. Plastics are synthesized in laboratories or plants. Thus, they are man-made chemicals.

Complete answer:
Plastics are also extracted from petroleum resources. Chemically, we can classify plastics as hydrocarbons. Hydrocarbons contain two elements carbon and hydrogen.
A polymer contains several repeating units called monomers. Plastics are considered polymers because, like polymers, plastics are high molecular weight compounds containing several repeating units. These repeating units are the basic molecules called monomers.
You can consider a simple analogy of several similarly railroad cars linked together with each other to form a train having huge length.
As an example, consider the plastic polyethylene. We can call polyethylene as polythene.
Polythene contains more than 50000 monomers linked together to form a long chain. The monomer is ethylene. Ethylene contains two carbon atoms, four hydrogen atoms and a carbon-carbon double bond.
On broadly classifying the process of polymerization in two types, one is addition polymerization and other is condensation polymerization. In addition, polymerization, the monomer units add to form long polymer chains. For example, several ethylene molecules add to form polythene. Ethylene molecules contain carbon-carbon double bonds. But polythene contains only carbon-carbon single bonds. Double bonds are not present in polythene.

Hence, plastic is known as polymer.

Note: In condensation polymerization, monomer units undergo condensation reaction to form polymer. During condensation, some simple molecules such as water are eliminated.