Of the 92 natural elements, 25 are essential for life. There are six main elements that are the fundamental building blocks of life. They are, in order of least to most common: sulfur, phosphorous, oxygen, nitrogen, carbon, and hydrogen.
- 2.4: Organic Compounds
- The basis of life is carbon. Carbon's importance comes mainly from the enormous variety of structures that it can form due to its unusual four valence electrons. Most important of these structures is the carbon chain, which forms the "backbone" of fatty acids and carbohydrates, among other organic molecules. Other elements do share properties similar to carbon, in this regard. However, they are not as prevalent on earth as carbon.