These bonding sites are arranged this way because in the carbon atom there are four electrons in the second energy level. Carbon atoms are usually involved in covalent bonds. Carbon can combine with 4 other atoms by forming 4 separate single covalent bonds with other atoms. Some organic molecules contain triple covalent bonds. Atoms commonly found in organic molecules are hydrogen, oxygen, nitrogen, sulfur, phophorus and of course carbon.
All organic molecules have a carbon skeleton that is composed of rings or chains of carbons.
Attached to the carbon skeleton are specific combinations of atoms called functional groups . Functional groups determine specific chemical properties. Examples of functional groups are the alcohol group, methyl group, amino group, carboxylic acid group, phosphate group, carbonyl group . There are four major types of organic molecules. These are Carbohydrates , Lipids , Proteins and Nucleic Acids .