Question

what is resonance and state it's effect?

Answer 1

Resonance effect describes the polarity produced in a molecule by interaction between a lone pair electron and a pi bond or the interaction of two pi bonds in adjacent atoms. It is usually found in molecules with conjugated double bonds or in molecules having at least one lone pair and one double bond. Understanding resonance is important in understanding stability of the compound and its energy state.

There are two types:

1.Positive Resonance Effect (+R effect)

When the transfer of electrons is away from an atom or substituent group attached to the conjugated system (presence of alternate single and double bonds in an open-chain or cyclic system) due to resonance, we call this effect as positive resonance effect. Some of the substituent groups which attribute to positive resonance effect are – COOH, –CHO, >C=O, – CN, –NO2, etc.

2.Negative Resonance Effect (- R effect)

When the transfer of electrons is towards the atom or substituent group attached to the conjugated system (presence of alternate single and double bonds in an open-chain or cyclic system) due to resonance, we call this effect as negative resonance effect. Some of the substituent groups which attribute to negative resonance effect are – COOH, –CHO, >C=O, – CN, –NO2, etc.

Answer 2

resonance is essential for solving problems of increased vibration. resonance is a condition that can occur in mechanical structures and can be described as sensitivity to a certain vibration frequency.