What do the terms 'mesomeric effect' and 'inductance effect' mean?

What do the terms 'mesomeric effect' and 'inductance effect' mean?


1 Answers

sumit kumar
askIITians Faculty 13 Points
8 years ago
Mesomeric Effect or resonance effcet:
There are many organic molecules which can not be represented by a single lewis structure. In turn, they are assigned more than one structure called canonical forms or contributing of resonating structures. The phenomenon exhibited by such compounds is called resonance. For example, 1, 3 – butadiene has following resonance structure.
While drawing these canonical forms, the prime thing that has to be kept in mind is that the relative position of any of the atom should not change while we are allowed to change the relative positions of p - bonded electron pair or distribution of charge to other atoms. Also remember that it is not the case that some molecules have one canonical form and some have another form. All the molecules of the substance have the same structure. That structure is always the same all the time and is a weighted average of all the canonical forms.
Inductive effect:
In a covalent bond between the two dissimilar atoms, the electron pair forming the bond is never shared absolutely equally between the two atoms but is attracted a little more towards the more electronegative atom of the two, eg. The electron pair forming the C–X bond is somewhat more attracted towards the atom X with the result – it attains a partial negative charge (–\delta) while the carbon atoms attain a partial positive charge (+\delta)
On the other hand, in compounds like C–Y, where Y in an electropositive element or group i.e., C is more electronegative than Y, the electron pair forming the C–Y bond is somewhat displaced towards the carbon atom and thus C and Y attain partial negative and partial positively charges respectively.
Thanks & Regards
Sumit kumar
askIITians Faculty

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