Can you explain the question more?
Well a basic explanation is that some elements have enough electrons to be considered stable. These elements do not need to react with other elements to gain more electrons. Reactive elements are no where near stable; they respond with other elements in order to become stable. The more unstable, the harsher the reaction is.
Answer:
Due to the chemical versatility of carbon atoms
Explanation:
Carbon is a very important element and it is commonly found in many varieties of chemical compounds. They are also found to be present in space in various amount. It is often considered to be versatile because they are capable of forming single, double, as well as triple bonds. This enables them to make single and branched chains. They also form ring chains when combined with other atoms of carbon.
It is because of this versatility of carbon atoms, there forms complex variety of organic molecules.