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  2. Valence (chemistry) - Wikipedia

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

    The valence is the combining capacity of an atom of a given element, determined by the number of hydrogen atoms that it combines with. In methane, carbon has a valence of 4; in ammonia, nitrogen has a valence of 3; in water, oxygen has a valence of 2; and in hydrogen chloride, chlorine has a valence of 1. Chlorine, as it has a valence of one ...

  3. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    Nitrogen is the least electronegative atom of the two, so it is the central atom by multiple criteria. Count valence electrons. Nitrogen has 5 valence electrons; each oxygen has 6, for a total of (6 × 2) + 5 = 17. The ion has a charge of −1, which indicates an extra electron, so the total number of electrons is 18. Connect the atoms by ...

  4. Nitrogen - Wikipedia

    en.wikipedia.org/wiki/Nitrogen

    Nitrogen must first be processed, or "fixed", into a plant-usable form, usually ammonia. Some nitrogen fixation is done by lightning strikes producing the nitrogen oxides, but most is done by diazotrophic bacteria through enzymes known as nitrogenases (although today industrial nitrogen fixation to ammonia is also significant). When the ammonia ...

  5. Periodic trends - Wikipedia

    en.wikipedia.org/wiki/Periodic_trends

    However, as we move down in a group, the number of valence electrons generally does not change. Hence, in many cases the elements of a particular group have the same valency. However, this periodic trend is not always followed for heavier elements, especially for the f-block and the transition metals. These elements show variable valency as ...

  6. Frenzel maneuver - Wikipedia

    en.wikipedia.org/wiki/Frenzel_maneuver

    The maneuver is used to equalize pressure in the middle ear. Today, the maneuver is also performed by scuba divers, free divers and by passengers on aircraft as they descend. [1] [2] [3] The trapped air inside the mouth and nasal cavities is compressed by the movement of the tongue or larynx while doing Frenzel maneuver.

  7. Valence electron - Wikipedia

    en.wikipedia.org/wiki/Valence_electron

    Thus, although a nickel atom has, in principle, ten valence electrons (4s 2 3d 8), its oxidation state never exceeds four. For zinc, the 3d subshell is complete in all known compounds, although it does contribute to the valence band in some compounds. [4] Similar patterns hold for the (n−2)f energy levels of inner transition metals.

  8. Octet rule - Wikipedia

    en.wikipedia.org/wiki/Octet_rule

    The bonding in carbon dioxide (CO 2): all atoms are surrounded by 8 electrons, fulfilling the octet rule.. The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.

  9. Pnictogen - Wikipedia

    en.wikipedia.org/wiki/Pnictogen

    Nitrogen trifluoride is the only stable nitrogen trihalide, with nitrogen trichloride, nitrogen tribromide, and nitrogen triiodide being explosive—nitrogen triiodide being so shock-sensitive that the touch of a feather detonates it (the last three actually feature nitrogen in the −3 oxidation state).