chon

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Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur

CHON is an mnemonic acronym for the four most common elements in living organisms: carbon, hydrogen, oxygen, and nitrogen. These four elements are also notable for being the least massive (and having the lowest atomic number) in their group in the periodic table.

Sometimes the acronym CHONP is used to include the element phosphorus which, besides being crucial in DNA and RNA, and it forms the core of the phosphate groups present in ATP and ADP.

Further, the acronym CHONPS is sometimes used, which stands for carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. Sulfur is used in the amino acids cysteine and methionine.

Excluding noble gases, the CHON elements are also some of the most abundant - carbon (4^th most abundant), hydrogen (most abundant), oxygen (3^rd) and nitrogen (6^th). The other abundant elements, helium and neon, are both inert - they do not react with other elements. These represent six of the 26^{[verification needed]} elements commonly found in living things.

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 Earth's history and these meteorites may have been crucial in the formation of life on Earth.

CHON in science fiction

CHON is featured in science fiction as the elements needed to sustain life in space colonies or as a lucrative space industry. In particular, CHON is featured prominently in Frederik Pohl's Gateway which has an overpopulated Earth with 25 billion inhabitants. In this novel the protagonist starts out as oil shale miner, with the oil being used as a feedstock for manufacturing synthetic food. In the sequel Beyond the Blue Event Horizon an alien "food factory" is discovered in the Oort cloud. This factory is mining carbonaceous asteroids which are high in CHON elements, and synthesize edible food from them.

See also

• Carbon-based life

External links

• Essay on how CHON elements formed life