All organic compounds have a hydrocarbon part

Drawing hydrocarbon skeletons and appreciating the variety of ways in which carbon atoms can be bonded to each other is a good introduction to organic chemistry because all organic compounds are hydrocarbons in part.
 
Both saturated and unsaturated hydrocarbons (1, 2) can have the same carbon skeleton.
Most organic compounds contain bonds from carbon to atoms other than H.
3 and 4 are two examples that have the same carbon skeleton as 1.
 
1 2
34


Compounds 56, 7 and 8 have the same carbon skeleton.  
These illustrate that carbon-oxygen double bonds are very common in organic compounds.
 


CH3CH2CH2CH3
6
78


The hydrocarbon portion of every organic molecule structure is an important aspect of its structure. However, you will learn that the saturated hydrocarbon portions of organic molecules are usually not involved in reactions.