Molecules consisted only of hydrogen and carbon elements are called hydrocarbons, or organic molecules since they are found in living things.
Depending on their structure and the chemical bonds between the elements, they can be divided into three groups :
1) saturated ( which have only single bonds between the hydrogen and carbon atoms eg. CH3-CH3 )
2)non-saturated ( which have two or three bonds between the carbon and hydrogen atoms eg. CH2=CH2)
3) aromatic (having the aromatic ring )
