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  2. Oxygen - Wikipedia

    en.wikipedia.org/wiki/Oxygen

    Water in equilibrium with air contains approximately 1 molecule of dissolved O 2 for every 2 molecules of N 2 (1:2), compared with an atmospheric ratio of approximately 1:4. The solubility of oxygen in water is temperature-dependent, and about twice as much (14.6 mg/L) dissolves at 0 °C than at 20 °C (7.6 mg/L).

  3. Atmosphere of Earth - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Earth

    The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by Earth's gravity.

  4. Ozone - Wikipedia

    en.wikipedia.org/wiki/Ozone

    Ozone (/ ˈoʊzoʊn /) (or trioxygen) is an inorganic molecule with the chemical formula O. 3. It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope O. 2, breaking down in the lower atmosphere to O.

  5. Allotropes of oxygen - Wikipedia

    en.wikipedia.org/wiki/Allotropes_of_oxygen

    There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: Atomic oxygen (O1), a free radical. 2), one of two metastable states of molecular oxygen.

  6. Ozone–oxygen cycle - Wikipedia

    en.wikipedia.org/wiki/Ozone–oxygen_cycle

    If an oxygen atom and an ozone molecule meet, they recombine to form two oxygen molecules: 4. ozone conversion: O 3 + O → 2 O 2. Two oxygen atoms may react to form one oxygen molecule: 5. oxygen recombination: 2O + A → O 2 + A as in reaction 2 (above), A denotes another molecule or atom, like N 2 or O 2 required for the conservation of ...

  7. Geological history of oxygen - Wikipedia

    en.wikipedia.org/wiki/Geological_history_of_oxygen

    Geological history of oxygen. Before photosynthesis evolved, Earth's atmosphere had no free diatomic oxygen (O 2). [2] Small quantities of oxygen were released by geological [3] and biological processes, but did not build up in the atmosphere due to reactions with reducing minerals. Oxygen began building up in the atmosphere at approximately 1. ...

  8. Oxygen evolution - Wikipedia

    en.wikipedia.org/wiki/Oxygen_evolution

    Oxygen evolution. Oxygen evolution is the process of generating molecular oxygen (O 2) by a chemical reaction, usually from water. Oxygen evolution from water is effected by oxygenic photosynthesis, electrolysis of water, and thermal decomposition of various oxides. The biological process supports aerobic life.

  9. Oxygen cycle - Wikipedia

    en.wikipedia.org/wiki/Oxygen_cycle

    Oxygen cycle refers to the movement of oxygen through the atmosphere (air), biosphere (plants and animals) and the lithosphere (the Earth’s crust). The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as well as how it is used. The oxygen cycle is the biogeochemical cycle of oxygen atoms between different ...