oksügeenid

Oksügeenid are the chemical species associated with the element oxygen. The element has the symbol O and atomic number 8. The most common forms of oksügeenid in nature are diatomic oxygen (O2), which makes up about 21% of Earth's atmosphere, and ozone (O3), a triatomic form concentrated in the stratosphere where it forms the ozone layer. A monatomic form of oxygen exists only fleetingly under high-energy conditions and in excited states.

Oxygen is the third most abundant element in the universe by mass and is a major constituent of Earth’s crust and oceans. In the atmosphere, O2 is essential for aerobic respiration in most organisms. The oxygen cycle describes the movement of oksügeenid through photosynthesis, respiration, and geological and chemical processes.

Industrially, oksügeenid are produced mainly by fractional distillation of liquid air or by cryogenic separation. They are used in steelmaking, chemical synthesis, metal cutting and welding, medical oxygen therapy, and water treatment. Ozone, produced from oksügeenid by electrical discharge or UV irradiation, is used for disinfection and oxidation processes, though it is toxic at ground level and requires careful handling.

Isotopically, oksügeenid include several stable isotopes, primarily 16O, with 17O and 18O also occurring in nature. They are chemically reactive and, in high concentrations or in pure forms, oxygen supports combustion and can pose fire hazards. Overall, oksügeenid play a crucial role across chemistry, biology, and industry.