chemical element with the chemical symbol O and atomic number 8. The word oxygen derives from roots in Greek, 18th century, Antoine Lavoisier coined the name oxygen from Greek .Oxygen has a valency of 2. usually bonded to other elements covalently or ionically. Examples for oxygen-containing compounds include water (H2O), sand (silica, SiO2), and rust (iron oxide, Fe2O3).
Diatomic oxygen (O2) is one of the two major components of air (20.95%). It is produced by plants during photosynthesis, and is necessary for aerobic respiration in animals. Triatomic oxygen (ozone, O3) forms through radiation in the upper layers of the atmosphere and acts as a shield against UV radiation.
