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  2. Oxygen - Wikipedia

    en.wikipedia.org/wiki/Oxygen

    Oxygen is a chemical element; it has symbol O and atomic number 8. 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. Oxygen is the most abundant element in Earth's crust, and after hydrogen and helium, it ...

  3. Hydrogen bond - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_bond

    Water is unique because its oxygen atom has two lone pairs and two hydrogen atoms, meaning that the total number of bonds of a water molecule is up to four. [40] The number of hydrogen bonds formed by a molecule of liquid water fluctuates with time and temperature. [41]

  4. Water - Wikipedia

    en.wikipedia.org/wiki/Water

    Tetrahedral structure of water. In a water molecule, the hydrogen atoms form a 104.5° angle with the oxygen atom. The hydrogen atoms are close to two corners of a tetrahedron centered on the oxygen. At the other two corners are lone pairs of valence electrons that do not participate in the bonding. In a perfect tetrahedron, the atoms would ...

  5. Chemical bonding of water - Wikipedia

    en.wikipedia.org/wiki/Chemical_bonding_of_water

    Chemical bonding of water. Water (H2O) is a simple triatomic bent molecule with C 2v molecular symmetry and bond angle of 104.5° between the central oxygen atom and the hydrogen atoms. Despite being one of the simplest triatomic molecules, its chemical bonding scheme is nonetheless complex as many of its bonding properties such as bond angle ...

  6. Allotropes of oxygen - Wikipedia

    en.wikipedia.org/wiki/Allotropes_of_oxygen

    The common allotrope of elemental oxygen on Earth, O2, is generally known as oxygen, but may be called dioxygen, diatomic oxygen, molecular oxygen, dioxidene or oxygen gas to distinguish it from the element itself and from the triatomic allotrope ozone, O3. As a major component (about 21% by volume) of Earth's atmosphere, elemental oxygen is ...

  7. Water splitting - Wikipedia

    en.wikipedia.org/wiki/Water_splitting

    Water splitting is the chemical reaction in which water is broken down into oxygen and hydrogen: [1] 2 H 2 O → 2 H 2 + O 2. Efficient and economical water splitting would be a technological breakthrough that could underpin a hydrogen economy. A version of water splitting occurs in photosynthesis, but hydrogen is not produced.

  8. Oxygen compounds - Wikipedia

    en.wikipedia.org/wiki/Oxygen_compounds

    Oxygen compounds. Water (H 2 O) is the most familiar oxygen compound. The oxidation state of oxygen is −2 in almost all known compounds of oxygen. The oxidation state −1 is found in a few compounds such as peroxides. Compounds containing oxygen in other oxidation states are very uncommon: − 1⁄2 (superoxides), − 1⁄3 (ozonides), 0 ...

  9. Reactive oxygen species - Wikipedia

    en.wikipedia.org/wiki/Reactive_oxygen_species

    In chemistry and biology, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (O2), water, and hydrogen peroxide. Some prominent ROS are hydroperoxide (O 2 H), superoxide (O 2-), [ 1 ] hydroxyl radical (OH.), and singlet oxygen. [ 2 ] ROS are pervasive because they are readily produced from O 2, which is ...