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  2. Oxygen - Wikipedia

    en.wikipedia.org/wiki/Oxygen

    At standard temperature and pressure, two oxygen atoms will bind covalently to form dioxygen, a colorless and odorless diatomic gas with the chemical formula O 2. Dioxygen gas currently constitutes 20.95% molar fraction of the Earth's atmosphere, though this has changed considerably over long periods of time in Earth's history.

  3. Oxidation state - Wikipedia

    en.wikipedia.org/wiki/Oxidation_state

    2 has an overall charge of −1, so each of its two equivalent oxygen atoms is assigned an oxidation state of − ⁠ 1 / 2 ⁠. This ion can be described as a resonance hybrid of two Lewis structures, where each oxygen has an oxidation state of 0 in one structure and −1 in the other. For the cyclopentadienyl anion C 5 H −

  4. Isotopes of oxygen - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_oxygen

    Oxygen-15 is a radioisotope, often used in positron emission tomography (PET). It can be used in, among other things, water for PET myocardial perfusion imaging and for brain imaging. [ 20 ] [ 21 ] It has an atomic mass of 15.003 0656 (5) , and a half-life of 122.266(43) s .

  5. Allotropes of oxygen - Wikipedia

    en.wikipedia.org/wiki/Allotropes_of_oxygen

    Triatomic oxygen (ozone, O 3) is a very reactive allotrope of oxygen that is a pale blue gas at standard temperature and pressure. Liquid and solid O 3 have a deeper blue color than ordinary O 2, and they are unstable and explosive. [5] [6] In its gas phase, ozone is destructive to materials like rubber and fabric and is damaging to lung tissue ...

  6. Formal charge - Wikipedia

    en.wikipedia.org/wiki/Formal_charge

    Formal charges in ozone and the nitrate anion. In chemistry, a formal charge (F.C. or q*), in the covalent view of chemical bonding, is the hypothetical charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms, regardless of relative electronegativity.

  7. Atomicity (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Atomicity_(chemistry)

    Atomicity is the total number of atoms present in a molecule of an element. For example, each molecule of oxygen (O 2) is composed of two oxygen atoms. Therefore, the atomicity of oxygen is 2. [1] In older contexts, atomicity is sometimes equivalent to valency. Some authors also use the term to refer to the maximum number of valencies observed ...

  8. Valence (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Valence_(chemistry)

    Thus, each sulfur atom is hexavalent or has valence 6, but has oxidation state +5. In the dioxygen molecule O 2, each oxygen atom has 2 valence bonds and so is divalent (valence 2), but has oxidation state 0. In acetylene H−C≡C−H, each carbon atom has 4 valence bonds (1 single bond with hydrogen atom and a triple bond with the other ...

  9. Charge number - Wikipedia

    en.wikipedia.org/wiki/Charge_number

    In that case, the charge of an ion could be written as =. The charge number in chemistry normally relates to an electric charge. This is a property of specific subatomic atoms. These elements define the electromagnetic contact between the two elements. A chemical charge can be found by using the periodic table.