Carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur are the six most important chemical elements whose covalent combinations make up most biological molecules on Earth. All of these elements are nonmetals.
In a human body, the four elements—C, H, O, and N—compose about 96% of the weight, and major minerals (macrominerals) and minor minerals (also called trace elements) compose the remainder.
Sulfur is contained in the amino acids cysteine and methionine.
Phosphorus is contained in phospholipids, a class of lipids that are a major component of all cell membranes, as they can form lipid bilayers, which keep ions, proteins, and other molecules where they are needed for cell function, and prevent them from diffusing into areas where they should not be. Phosphate groups are also an essential component of the backbone of nucleic acids (general name for DNA & RNA) and are required to form ATP – the main molecule used as energy powering the cell in all living creatures.
Carbonaceous asteroids are rich in CHON elements.
These asteroids are the most common type, and frequently collide with Earth as meteorites. Such collisions were especially common early in Earths history, and these impactors may have been crucial in the formation of the planets oceans.
The simplest compounds to contain all of the CHON elements are isomers fulminic acid (HCNO), isofulminic acid (HONC), cyanic acid (HOCN) and isocyanic acid (HNCO), having one of each atom.