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  2. Resonance (chemistry) - Wikipedia

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

    Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.

  3. Cyclopentadienyl anion - Wikipedia

    en.wikipedia.org/wiki/Cyclopentadienyl_anion

    Resonance structures of the cyclopentadienyl anion The cyclopentadienyl anion is a planar, cyclic , regular- pentagonal ion; it has 6 π-electrons (4 n + 2, where n = 1), which fulfills Hückel's rule of aromaticity.

  4. Clar's rule - Wikipedia

    en.wikipedia.org/wiki/Clar's_rule

    Clar's rule states that for a benzenoid polycyclic aromatic hydrocarbon (i.e. one with only hexagonal rings), the resonance structure with the largest number of disjoint aromatic π-sextets is the most important to characterize its chemical and physical properties. Such a resonance structure is called a Clar structure. In other words, a ...

  5. Mesomeric effect - Wikipedia

    en.wikipedia.org/wiki/Mesomeric_effect

    In chemistry, the mesomeric effect (or resonance effect) is a property of substituents or functional groups in a chemical compound.It is defined as the polarity produced in the molecule by the interaction of two pi bonds or between a pi bond and lone pair of electrons present on an adjacent atom. [1]

  6. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    Expressing resonance when drawing Lewis structures may be done either by drawing each of the possible resonance forms and placing double-headed arrows between them or by using dashed lines to represent the partial bonds (although the latter is a good representation of the resonance hybrid which is not, formally speaking, a Lewis structure ...

  7. C5H4O - Wikipedia

    en.wikipedia.org/wiki/C5H4O

    This page was last edited on 15 September 2023, at 20:11 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply.

  8. Electrophilic aromatic directing groups - Wikipedia

    en.wikipedia.org/wiki/Electrophilic_aromatic...

    On the other hand, the nitrobenzene resonance structures have positive charges around the ring system: The nitro group can withdraw electron density through resonance. Attack occurs at the meta position, since the (partial) formal positive charges at the ortho and para positions indicate electron deficiency at these positions.

  9. Enol - Wikipedia

    en.wikipedia.org/wiki/Enol

    In organic chemistry, enols are a type of Functional group or intermediate in organic chemistry containing a group with the formula C=C(OH) (R = many substituents). The term enol is an abbreviation of alkenol, a portmanteau deriving from "-ene"/"alkene" and the "-ol".