Final answer:
Carbon is called the 'backbone' of organic chemistry because it can form four stable covalent bonds, allowing for a vast variety of organic molecules essential for life. Hydrogen and oxygen cannot replicate this complex bonding due to their own chemical limitations.
Step-by-step explanation:
Carbon is referred to as the “backbone” molecule of organic chemistry because of its unique ability to bind with various elements, including itself, through stable covalent bonds. This unique feature allows carbon to construct a wide variety of complex structures such as long chains, branching chains, and rings, which are fundamental in forming organic molecules. Due to carbon's versatility, it serves as the fundamental component of macromolecules like proteins, nucleic acids, carbohydrates, and lipids, which are essential for life. In contrast, other elements like hydrogen (H) or oxygen (O) cannot form the same long, interconnected carbon-based structures due to their own chemical properties.
While hydrogen's single electron limits it to forming only one bond, oxygen's six valence electrons lead it to typically form two bonds. Neither has the capacity to create the extensive and diverse molecular structures associated with living organisms, unlike carbon with its four valence electrons that allow the formation of up to four bonds, thus enabling a vast number of potential biochemical compounds.