Get to know CHNOPS

Learn the recognizable chemical properties of these key elements. They make up 98% of living matter on Earth.

  • 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.


CHNOPS stands for Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur. These six elements make up 98% of living matter on Earth! How does that help you? If you understand the chemical behavior of CHNOPS, you can understand almost all of biochemistry.
A chemistry lab with a desk and square storage boxes suggestive of a periodic table