oxigénen

Oxigénen is a chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, being the second lightest element in this group. Oxygen is a highly reactive nonmetal and an oxidizing agent that readily forms oxides with most elements. It is the most abundant element in the Earth's crust by mass, making up about 46.6% of the crust. Oxygen is also the third most abundant element in the universe by mass, after hydrogen and helium.

At standard temperature and pressure, two atoms of the element form a diatomic molecule with the formula O2, which is odorless and colorless. Oxygen is essential for life on Earth, as it is required for cellular respiration in most organisms. It is also a key component of water and many organic compounds. Industrially, oxygen is produced by fractional distillation of liquid air or by electrolysis of water.

The diatomic oxygen molecule, O2, is paramagnetic. Ozone, O3, is an allotrope of oxygen that is a much stronger oxidizing agent and is found in the Earth's stratosphere, where it absorbs most of the Sun's ultraviolet radiation. Oxygen plays a vital role in combustion processes and is used in many industrial applications, including steelmaking, welding, and in medical oxygen therapy.