Socratica

Carbon forms the backbone of many molecules in living organisms. With a valence of four, one atom of carbon can form a variety of different single or multiple bonds, which allow it to generate great diversity of chemical structures.

Hydrogen forms one single bond. If dropped by a molecule, it can increase the level of acidity. Hydrogen is also a fundamental part of all hydrocarbon structures, commonly found in energy-rich molecules.

Nitrogen is an essential part of the basic amine group in amino acids. As such it is a fundamental component of proteins. It is also found in nucleic acids: the "nitrogenous bases" that form the rungs of these ladder-like structures.

Oxygen in its molecular form (O2) is required for cellular respiration. In molecules, oxygen is a potent oxidizer (electron acceptor).

Phosphorus, in the form of the acidic phosphate group, is found in the backbone of DNA, the key genetic molecule of life. Phosphate is also an essential part of ATP, a molecule used as energetic currency in living things.

Sulfur is commonly found in proteins. When two amino acids join their sulfurs together, they form a stable structure known as a disulfide bridge. This is an essential underlying component of the 3-dimensional structure of common molecules in living organisms.