Oxygen
Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the halogen group on the periodic table and is a highly reactive nonmetallic element and oxidizing agent that readily forms compounds with most elements. By mass, oxygen is the third-most abundant element in the universe,
It is colorless, odorless, and tasteless, with the formula O2. Many major classes of orga
nic molecules in living organisms, such as proteins , nucleic acids, carbohydrates, and fats, contain oxygen. Oxygen is produced industrially by fractional distillation of liquefied air, use of zeolites with pressure cling to concentrate oxygen from air, electrolysis of water and other means. Uses of elemental oxygen include the production of steel, plastic sand textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy and life support systems in aircraft, submarine spaceflight and diving. 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. Structure
At standard temperature and pressure, oxygen is a colorless, odorless gas with the molecular formula O2, in which the two oxygen atoms are chemically bonded to each other with a spin triplet electron configuration. Physical properties
Oxygen is more soluble in water than nitrogen is. Water in equilibrium with air contains approximately 1 molecule of dissolved O2 for every 2 molecules of N2, compared to an atmospheric ratio of approximately 1:
