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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.
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 ...
In another case, the stereoelectronic effect can result in an increased contribution of one resonance structure over another, which leads to further consequences in reactivity. For 1,4- benzoquinone monoxime, there are significant differences in the physical properties and reactivities between C2-C3 double bond and C5-C6 double bond.
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]
A demonstration that how some well known 1,3-dipoles like ozone, nitro compounds and azides can be shown to have a resonance structure having 1,3 relationship between positive and negative formal charges. Known 1,3-dipoles are: Azides (RN 3) Ozone (O 3) Nitro compounds (RNO 2) Diazo compounds (R 2 CN 2) Some oxides. Azoxide compounds (RN(O)NR)
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 ...
Proton nuclear magnetic resonance (proton NMR, hydrogen-1 NMR, or 1 H NMR) is the application of nuclear magnetic resonance in NMR spectroscopy with respect to hydrogen-1 nuclei within the molecules of a substance, in order to determine the structure of its molecules. [1]
The rightmost structure in the diagram has a charge of -2 on the nitrogen atom. Applying the principle of electroneutrality this can be identified as only a minor contributor. Additionally as the most electronegative atom should carry the negative charge, then the triple bonded structure on the left is predicted to be the major contributor. [7]