User:Mahadik Kanak/sandbox

Oxygen is the element in periodic table having atomic no.8 and denoted as O. 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. On the Earth oxygen is the third most abundant element after hydrogen and helium in universe. At standard temperature and pressure, two atoms of oxygen bind to form dioxygen, a colorless and odorless diatomic gas with the formula O. Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. Oxygen in form of oxides makes up almost half of the Earth's crust.