Hydrocarbons are compounds made from carbon and hydrogen atoms joined by covalent bonds. Alkanes are saturated - they have only single bonds. Alkenes have a double bond - they are unsaturated. ... These polymer molecules are saturated.

Explanation:
Alkenes are hydrocarbons that contain at least one carbon-carbon double bond (-C=C-). Due to the presence of double bonds, alkenes are unsaturated compounds. This means that they have fewer hydrogen atoms per carbon atom than an equivalent alkane with the same number of carbon atoms.

What is unsaturation?
Unsaturation refers to the presence of double or triple bonds in a molecule. In organic chemistry, a compound is considered unsaturated if it contains one or more double or triple bonds between carbon atoms. Alkenes are unsaturated hydrocarbons because they contain at least one carbon-carbon double bond (-C=C-).

How do double bonds affect polarity?
Double bonds are made up of two pairs of electrons shared between two atoms. The unequal sharing of electrons in a double bond results in a polar covalent bond. The carbon atoms in an alkene have an electronegativity difference of about 0.4, which means that the electrons are not shared equally between the two atoms. This makes alkenes polar molecules.

Conclusion:
In conclusion, alkenes are unsaturated hydrocarbons that contain at least one carbon-carbon double bond. Due to the presence of double bonds, alkenes are unsaturated and have fewer hydrogen atoms per carbon atom than an equivalent alkane. Double bonds also make alkenes polar molecules.

The carbon compounds which are joined by double bond or by triple bond is known as unsaturated compound