Which property of carbon allows it to form a large number of compounds by bonding with itself and other elements?

Catenation is the unique property of an element to form long chains or rings by bonding with atoms of the same element. In carbon, this 'self-linking' ability is exceptionally strong, allowing it to create stable, complex backbones for millions of different organic compounds. Unlike other elements, the bond between two carbon atoms is very strong and stable. This means the chains don't easily fall apart, allowing for the formation of long straight chains, branched structures, and closed rings. Because carbon can keep adding to itself, it can form anything from a simple two-carbon gas (ethane) to massive, complex structures like DNA or synthetic plastics. While catenation provides the backbone, carbon's tetravalency allows other elements like hydrogen, oxygen, and nitrogen to 'plug in' to that backbone, creating the vast variety of substances we see in biology and chemistry.