* Structure of Ethylene: Ethylene has a double bond between the two carbon atoms. This double bond restricts rotation, meaning the atoms on either side of the double bond are locked in a specific arrangement.

* Geometric Isomerism: Geometric isomers, also known as cis-trans isomers, occur when there is restricted rotation around a bond, and different groups are attached to the atoms involved in the bond. To have geometric isomers, you need:

* A double bond or ring structure: This restricts rotation.

* Different groups attached to each carbon on the double bond: These groups need to be different to create distinct arrangements.

* Ethylene's Lack of Different Groups: Ethylene has two hydrogen atoms attached to each carbon atom on the double bond. Since the groups are identical, there's no way to create different spatial arrangements.

In summary: Ethylene has a double bond but lacks the necessary different groups to create distinct geometric isomers.