Functional groups are groups of atoms that confer similar properties onto otherwise dissimilar molecules. Carbon, nitrogen, oxygen, hydrogen, and phosphorus are a few of the elements involved in forming functional groups. Carbon can make four bonds. Nitrogen makes three, oxygen two, and hydrogen one. In the following figures, a single line represents one bond.
- Hydrocarbons are long chains of carbon and hydrogen ending with a methyl group. Hydrocarbons are hydrophobic and form the backbone of most organic molecules. Thus, be familiar with the structure since it will show up often. An example of a hydrocarbon is methane.
- Alcohols are characterized by a hydroxyl group. This group makes the compound polar and hydrophilic. Alcohols dissolve in water easily and are good fuels. An example of an alcohol is ethanol.
- Carboxylic acids are characterized by a carboxyl group. Also referred to as organic acids, these compounds are water soluble weak acids that are often aromatic. An example of a carboxylic acid is acetic acid (otherwise known as vinegar).
- Amines are characterized by an amino group. These compounds are water soluble weak bases. An example of an amine is ammonia.
- Aldehydes are characterized by an aldehyde group. These compounds are polar and hydrophilic. An example of an aldehyde is formaldehyde.
- Ketones are characterized by a ketone group. These compounds are polar and hydrophilic. Many steroids contain ketones. An example of a ketone is acetone.
- Organic phosphates are characterized by a phosphate group. These compounds are usually acidic. Organic phosphates can be found in ATP and in DNA.