Question

Which of the following conditions is not correct for resonating structures?
A. The contributing structures must have the same number of unpaired electrons.
B. The contributing structures must have similar energies.
C. The contributing structures should be so written that unlike charges reside on atoms that are far apart.
D. The positive charge should be present on the electropositive element and the negative charge on the electronegative element.

Answer 1

Hint:Resonance structure is a group of two or more Lewis structure combined as a single polyatomic species. This combination takes place as an electronic bonding which has fractional bonds and fractional charges.

Complete answer:
The resonance structure is the description of a Lewis structure which explains pairing of the electrons and the formation of chemical bonds. As the resonance structure explains the bonding of molecules and ions by merging their structure and completing their valency by forming a hybrid resonance structure. The energy which is required to build a resonance hybrid is called resonance energy. To build a resonance structure few conditions are need to be taken care:
1. The relative positions of all the atoms to be used in the structure must be the same.
2. The number of unpaired and paired electrons in the resonating forms must be the same so that a continous bond of one or the other type can occur.
3. The contributing structure must be of the same energy.
4. The more electropositive element should have a positive charge and the more negative one should have electronegative charge.
5. The positive charge atoms should not be in close proximity to each other similarly the unlike charges should not be greatly separated.

Therefore, in the above options the contributing structures should be so written that unlike charges residing on atoms that are far apart is not true.

Hence the correct option is Option (C) .

Note:
Resonance happens when the frequency of the oscillations of an object is raised by another object’s corresponding vibrations.