Inductive Effect Definition (Chemistry)

Inductive Effect Definition

The inductive effect is the effect that charge of a chemical bond has on the orientation on the adjacent bonds in a molecule. The inductive effect is a distance-dependent phenomenon that produces a permanent state of polarization.

The electron-withdrawing inductive effect is sometimes written as "the -I Effect" in literature.

How It Works

The electron density of a σ bond is not uniform when atoms of two different elements participate in the bond.

Electron clouds in a bond tend to orient themselves towards the more electronegative atom involved in the bond.

Inductive Effect Example

The inductive effect occurs in water molecules. The chemical bonds within a water molecule are more positively charged near the hydrogen atoms and more negatively charged near the oxygen atom. Thus, water molecules are polar. Note, however, the induced charge is weak and other factors can quickly overcome it. Also, the inductive effect is only active across short distances.

Inductive Effect and Acidity and Basicity

The inductive effect affects the stability as well as acidity or basicity of a chemical species. Electronegative atoms draw electrons toward themselves, which can stabilize a conjugate base. Groups that have -I effect on a molecule decrease its electron density. This makes the molecule electron deficient and more acidic.

Inductive Effect vs Resonance

Both the inductive effect and resonance relate to the distribution of electrons in a chemical bond, but they are two different effects.

Resonance is when there are multiple correct Lewis structures for a molecule because a double bond can form with equal probability between different atoms.

For example, ozone (O₃) has resonance forms. One might wonder whether the bonds formed between the oxygen atoms might be different lengths from each other, since single bonds are usually weaker/longer than double bonds.

In reality, the bonds between the atoms are the same length and strength as each other because resonance forms (drawn on paper) don't represent what's really going on within the molecule. It doesn't have a double bond and a single bond. Rather, the electrons are distributed evenly across the atoms, forming bonds that are intermediate between single and double bonds.