What is Oxygen atom?

     

Oxygen is the chemical element with the symbol O and atomic number 8.  It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds.  After hydrogen and helium, oxygen is the thirdmost abundant element in the universe by mass.  At standard temperature and pressure, two atoms of the element bind to form diloxygen, a colorless and odorlesss diatomic gas with the formula O2.

     Diatomic oxygen gas constitutes 20.95% of the Earth's atmosphere.  Oxygen makes up almost half of the Earth's crust in the form of oxides. Dioxygen provides the energy released in combustion and aerobic cellular respiration, and many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic  compounds of animal shells, teeth, and bond.  Most of the mass of living organisms is oxygen as a component of water, the major constitutent of lifeforms. 

     Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of liveing organisms.  Another form ( Allotrope) of oxygen, Ozone (O3)  strongly abosrbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation.  However, Ozone present at the surface is a byproduct of smog and thus a polluntant.

     Common uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.