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  2. Neighbouring group participation - Wikipedia

    en.wikipedia.org/wiki/Neighbouring_group...

    An aromatic ring can assist in the formation of a carbocationic intermediate called a phenonium ion by delocalising the positive charge. When the following tosylate reacts with acetic acid in solvolysis then rather than a simple S N 2 reaction forming B, a 48:48:4 mixture of A, B (which are enantiomers) and C+D was obtained. [7] [8]

  3. Organic photochemistry - Wikipedia

    en.wikipedia.org/wiki/Organic_photochemistry

    Inspection of the alternative phenonium-type species, in which an aryl group has begun to migrate to the beta-carbon, reveals the greater electron delocalization with a substituent para on the migrating aryl group and thus a more stabilized pathway.

  4. Onium ion - Wikipedia

    en.wikipedia.org/wiki/Onium_ion

    In chemistry, an onium ion is a cation formally obtained by the protonation of mononuclear parent hydride of a pnictogen (group 15 of the periodic table), chalcogen (group 16), or halogen (group 17). The oldest-known onium ion, and the namesake for the class, is ammonium , NH + 4 , the protonated derivative of ammonia , NH 3 .

  5. Nonclassical ion - Wikipedia

    en.wikipedia.org/wiki/Nonclassical_ion

    Structure of the 2-norbornyl cation, an iconic nonclassical ion. The structure was deduced from X-ray crystallography. C-C bond lengths not labeled are normal (ca. 1.5 Å). [1] In chemistry, a nonclassical ion usually refers to carbonium ions, a family of organic cations. They are characterized by delocalized three-center, two-electron bonds ...

  6. Ionization energies of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Ionization_energies_of_the...

    For each atom, the column marked 1 is the first ionization energy to ionize the neutral atom, the column marked 2 is the second ionization energy to remove a second electron from the +1 ion, the column marked 3 is the third ionization energy to remove a third electron from the +2 ion, and so on.

  7. Ionic strength - Wikipedia

    en.wikipedia.org/wiki/Ionic_strength

    The molar ionic strength, I, of a solution is a function of the concentration of all ions present in that solution. [3]= = where one half is because we are including both cations and anions, c i is the molar concentration of ion i (M, mol/L), z i is the charge number of that ion, and the sum is taken over all ions in the solution.

  8. Hydronium - Wikipedia

    en.wikipedia.org/wiki/Hydronium

    In chemistry, hydronium (hydroxonium in traditional British English) is the cation [H 3 O] +, also written as H 3 O +, the type of oxonium ion produced by protonation of water.It is often viewed as the positive ion present when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in solution give up a proton (a positive hydrogen ion, H +) to the surrounding water molecules (H 2 O).

  9. Ionic radius - Wikipedia

    en.wikipedia.org/wiki/Ionic_radius

    Ionic radius, r ion, is the radius of a monatomic ion in an ionic crystal structure. Although neither atoms nor ions have sharp boundaries, they are treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.