About

It is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. Diatomic oxygen gas constitutes 20. 8% of the Earth's atmosphere. As compounds including oxides, the element makes up almost half of the Earth's crust. Oxygen was discovered independently by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier; and Joseph Priestley in Wiltshire, in 1774, but Priestley is often given priority because his work was published first. The name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. Its name derives from the Greek roots ὀξύς, "acid", literally "sharp", referring to the sour taste of acids and -γενής, -gene, "producer", literally "begetter", because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition. Oxygen is a highly reactive element and is capable of combining with most other elements. It is required by all living organisms for cellular respiration and is a key component of both organic and inorganic compounds such as proteins, nucleic acids, carbohydrates, and fats. Many of the Earth's processes are influenced by oxygen, such as its role in the carbon cycle, the nitrogen cycle, and the water cycle. Oxygen is the most abundant element by mass in the Earth's biosphere, air, sea, and land. Oxygen has a wide range of industrial and medical applications, including in combustion reactions, steel production, water treatment, and in the medical field as a therapeutic gas and a respiratory support. It is also used in the production of ozone, plastics, and certain chemicals. Despite its vital importance, oxygen can also be highly reactive and potentially toxic, contributing to oxidative stress and various health issues.