kislorod

Kislorod, known in English as oxygen, is the chemical element with symbol O and atomic number 8. It is a colorless, odorless gas at room temperature and pressure. In its most common form, O2, two oxygen atoms share a double bond. Oxygen is paramagnetic due to two unpaired electrons and forms a wide range of oxides with nearly all elements.

It is the third most abundant element in the universe by mass and accounts for about 21 percent of Earth's atmosphere. On Earth, most oxygen is bound in minerals, oxides, and silicates, while a smaller portion exists as molecular O2 in the air and water. A reactive allotrope, ozone (O3), is formed by ultraviolet light and helps shield living things from harmful radiation, though ozone at ground level is toxic.

Production and uses: industrially, oxygen is produced mainly by fractional distillation of liquid air or other air-separation methods. It is widely used in steelmaking and metal fabrication, chemical synthesis, respiration support in medicine, and as an oxidizer in rocket propulsion (liquid oxygen). It also supports combustion and is employed in water treatment and various oxidation processes.

Biological and ecological role: oxygen is essential for aerobic respiration, enabling energy production in most multicellular organisms. Photosynthetic organisms, including plants and algae, generate atmospheric oxygen, sustaining the oxygen cycle and supporting life on Earth.

History and naming: oxygen was identified in the 1770s by Carl Wilhelm Scheele and Joseph Priestley. Antoine Lavoisier coined the name oxygen, from Greek oxys, “sharp,” and genes, “producer,” reflecting an early assumption about acids that was later revised.