Difference Between Inductive Effect and Resonance Effect

Main Difference – Inductive Effect vs Resonance Effect

Inductive effect is the effect caused by the induced electrical charges in atoms of a molecule. This charge induction occurs due to the differences in the electronegativity values of atoms. Atoms with a high electronegativity tends to attract bond electrons towards itself. However, resonance effect is different from inductive effect. The resonance effect of a molecule arises when there are double bonds in that molecule. The main difference between inductive effect and resonance effect is that inductive effect describes the transmission of electrical charges between atoms in a molecule whereas resonance effect describes the transmission of electron pairs between atoms in a molecule.

Key Areas Covered

1. What is Inductive Effect
      – Definition and Mechanism
2. What is Resonance Effect
      – Definition and Mechanism
3. What is the Difference Between Inductive Effect and Resonance Effect
      – Comparison of Key Differences

Key Terms: Electronegativity, Inductive Effect, Polarity, Resonance Effect

What is Inductive Effect

Inductive effect is the effect that is caused by the transmission of an electrical charge throughout a chain of atoms. This charge transmission will finally result in a fixed electrical charge on atoms. The inductive effect occurs due to the differences in the electronegative values of atoms of a molecule.

An atom with a higher electronegativity tends to attract electrons towards themselves than lower electronegative atoms do. Therefore, when a highly electronegative atom and a low electronegative atom are in a covalent bond, the bond electrons are attracted towards the highly electronegative atom. This induces the low electronegative atom to get a partially positive charge. The highly electronegative atom will get a partial negative charge. This is called bond polarization.

The inductive effect is found in two ways as follows.

Electron Withdrawing Inductive Effect

This arises when a highly electronegative atom or a group is attached to a molecule. This atom or group will attract electrons from the rest of the molecule.

Electron Releasing Inductive Effect

This effect is seen when groups like alkyl groups are attached to a molecule. These groups are less electron-withdrawing and tend to give electrons to the rest of the molecule.

Figure 1: Inductive Effect of Different Groups

The inductive effect has a direct effect on the stability of molecules, especially organic molecules. If a carbon atom has a partial positive charge, an electron releasing group such as an alkyl group can reduce or remove this partial positive charge by providing electrons. Then the stability of that molecule is increased.

What is Resonance Effect

Resonance effect describes the effect on the stability of a molecule due to the interaction between pi bond electrons. Lone electron pairs can also contribute to the resonance of a molecule if there are any lone pairs present on atoms of the molecule.

The resonance effect causes the delocalization of electrons between atoms. Molecules having double bonds are involved in resonance. In order to determine the real structure of a molecule, we can use resonance structures. The real structure of a molecule is an intermediate structure obtained through resonance stabilization. Resonance structures are not isomers of the original molecule.

Figure 2: Resonance Effect in Nitrobenzene

If a particular molecule has no other resonance structures but only one structure, then it is the most stable structure in which the molecule can exist. Resonance structures are drawn as Lewis structures. By writing all possible structures for a molecule, we can determine the most stable intermediate structure for that molecule.

Difference Between Inductive Effect and Resonance Effect

Definition

Inductive Effect: Inductive effect is the effect that is caused by the transmission of an electrical charge throughout a chain of atoms.

Resonance Effect: Resonance effect describes the effect on the stability of a molecule due to the interaction between pi bond electrons.

Cause of Effect

Inductive Effect: The inductive effect occurs due to the polarization of bonds.

Resonance Effect: Resonance effect occurs due to the presence of single bonds and double bonds together.

Factors that Affect these Effects

Inductive Effect: The electronegativity values of atoms affect the degree of inductive effect.

Resonance Effect: The number of double bonds and their arrangement affects the resonance effect.

Conclusion

Inductive effect and resonance effect are related to the distribution of electrons between atoms of molecules. However, they are different terms when the mechanism of the formation of these effects are considered. The main difference between inductive effect and resonance effect is that inductive effect describes the transmission of electrical charges between atoms in a molecule whereas resonance effect describes the transmission of electron pairs between atoms in a molecule.

References:

1. Helmenstine, Anne Marie. “Here’s What the Inductive Effect Means in Chemistry.” ThoughtCo, Available here. Accessed 25 Aug. 2017.
2. “How to Study the Resonance Effect in Organic Chemistry.” WikiHow, WikiHow, 25 Aug. 2017, Available here. Accessed 25 Aug. 2017.

Image Courtesy:

1. “Inductive effect trends” By Manishearth at the English language Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
2. “Nitrobenzene resonance” By Ed (Edgar181) – Own work (Public Domain) via Commons Wikimedia