Final answer:
Carbon's unique properties allow for a wide range of molecular diversity. Organic molecules, made up of carbon atoms, can exhibit various shapes and sizes, allowing for a multitude of compounds. These carbon-based molecules are essential for living systems and are the focus of biochemistry.
Step-by-step explanation:
Carbon is unique among the other elements in that its atoms can form stable covalent bonds with each other and with atoms of other elements in a multitude of variations. The resulting molecules can contain from one to millions of carbon atoms. We previously surveyed organic chemistry by dividing its compounds into families based on functional groups. We begin with the simplest members of a family and then move on to molecules that are organic in the original sense that is, they are made by and found in living organisms. These complex molecules (all containing carbon) determine the forms and functions of living systems and are the subject of biochemistry.