Theory
Alkenes show both structural and geometrical isomerism.
Structural isomerism: These isomers differ in bonding arrangement of atoms or groups within the molecules. For example alkene with molecular formula C4H8 can be written as:
Geometrical isomerism: These isomers have different arrangements around C=C.
In cis, A is on the same side of the double bond and in trans, they lie opposite. These are also known as stereosiomers.
The both isomers differ in melting point, boiling point, dipole moment, solubility, etc.
Cis isomer is more polar than trans isomer.
Here the trans isomer is non-polar, as the dipole moments of C-Cl bonds cancel each other.
Further, a different notation is given to the compounds in which different atoms or group of atoms are attached to the double bond carbons, i.e. E-Z notation.
When the atoms of higher priorities are on the same side of double bond, it is Z-form. E-form is where the higher priority atoms are on opposite side of double bond.
