What are the common functional groups in organic chemistry?

Common functional groups in organic chemistry include hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, and methyl groups.

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. They are the "active" part of the molecule that determines how it will react with other substances. Let's look at some of the most common ones in more detail.

The hydroxyl group (-OH) is found in alcohols. It is polar due to the electronegative oxygen atom, making compounds with this group soluble in water.

The carbonyl group (C=O) is found in aldehydes and ketones. The carbon-oxygen double bond is highly polar, making these compounds reactive. In aldehydes, the carbonyl group is at the end of the carbon chain, while in ketones, it's in the middle.

The carboxyl group (-COOH) is found in carboxylic acids. This group is acidic because it can release a proton (H+) into solution, hence the name 'acid'.

The amino group (-NH2) is found in amines and amino acids. It is basic because it can accept a proton from solution.

The sulfhydryl group (-SH) is found in some amino acids. It can form a disulfide bond, which is important in the structure of proteins.

The phosphate group (-OPO3^2-) is found in nucleic acids and ATP. It is acidic and can transfer energy when the bond between the phosphate and the rest of the molecule is broken.

The methyl group (-CH3) is found in many organic molecules. It is nonpolar and thus does not mix with water.

Understanding these functional groups and their properties is key to understanding organic chemistry, as they determine how organic molecules behave and react with each other.