In chemistry, isomerism is the phenomenon in which more than one compounds have the same chemical formula but different chemical structures. Chemical compounds that have identical chemical formulae but differ in properties and the arrangement of atoms in the molecule are called isomers.

Ethylene, which has a carbon-carbon double bond, is one of the most important fundamental chemicals in the petrochemical industry as it is the source material for a variety of products such as polyethene resin, ethylene glycol, vinyl chloride resin, acetic acid, styrene, and alpha-olefin which are produced by polymerization, oxidation, alkylation, hydration, or the addition of halogen. The precise format of an ethylene derivative is given in the figure below, where R1,R2,R3,R4
 are atoms or atomic groups. We always suppose that R1
 and R2
 are on the same side of the carbon-carbon double bond, while R3
 and R4
 are on the other side. The carbon-carbon double bond in an ethylene derivative cannot rotate around the bond axis.

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    1 | In chemistry, isomerism is the phenomenon in which more than one compounds have the same chemical formula but different chemical structures. Chemical compounds that have identical chemical formulae but differ in properties and the arrangement of atoms in the molecule are called isomers.
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