Question

Inductive effect involves (1) delocalization of $\sigma$ electrons (2) displacement of $\sigma$ electrons (3) delocalization of $\pi$ electrons (4) displacement of $\pi$ electrons

Short answer

Option (2) displacement of $\sigma$ electrons

Step-by-step solution

- Understand Inductive Effect

The inductive effect refers to the electron-withdrawing or electron-donating effect transmitted through $\sigma$ bonds in a molecule due to the electronegativity of atoms.

- Identify the Electron Involved

The inductive effect specifically involves the shifting of $\sigma$ bond electrons due to the presence of electronegative atoms or groups.

- Analyze Options

Review the options given: $1)$ delocalization of $\sigma$ electrons, $2)$ displacement of $\sigma$ electrons, $3)$ delocalization of $\pi$ electrons, and $4)$ displacement of $\pi$ electrons. Out of these options, the inductive effect does not involve delocalization but rather displacement.

- Conclude the Correct Answer

Since the inductive effect involves displacement of $\sigma$ electrons, the correct option is $2$.

Key concepts

sigma electrons

Sigma electrons, often represented as $\sigma$ electrons, are the electrons found in sigma bonds. Sigma bonds are a type of covalent bond that forms through the head-to-head overlap of atomic orbitals. This overlap occurs directly between the nuclei of two atoms, making sigma bonds very strong.
In a molecule, sigma bonds form the basic framework that holds the atoms together. They are one of the main bonds keeping a molecule structurally stable.

Some key characteristics of sigma electrons include:

• Sigma bonds are the first bonds formed between two atoms.
• They are single bonds with a direct overlap of orbitals.
• They allow for free rotation around the bond axis.

Understanding sigma electrons is crucial for grasping more complex concepts like the inductive effect.

displacement of electrons

Displacement of electrons refers to the movement of electrons from one atom or group to another within a molecule. In the context of the inductive effect, this displacement involves $\sigma$ electrons.
The inductive effect occurs when an electronegative atom or group pulls the $\sigma$ electrons toward itself. This can create partial charges within the molecule, which can influence the molecule's reactivity and stability. Here’s what you need to know:

• Electronegativity differences drive the displacement of electrons.
• The effect is transmitted through $\sigma$ bonds.
• This displacement can make certain parts of the molecule more positive or negative.

It is important to differentiate this from the delocalization of electrons that occurs in $\pi$ bonds. The inductive effect is strictly about the displacement of $\sigma$ electrons.

electronegativity

Electronegativity is a measure of an atom’s ability to attract and hold onto electrons. In simple terms, it tells us how strongly an atom pulls electrons towards itself. Atoms with high electronegativity, like fluorine or oxygen, are very good at attracting electrons.
This property is essential for understanding the inductive effect:

• Electronegativity differences between atoms lead to the displacement of electrons.
• An atom with higher electronegativity will pull $\sigma$ electrons closer to itself.
• This causes one end of the molecule to become more charged than the other.

In molecules, electronegativity plays a crucial role in determining how electrons are distributed and how the molecule will behave in chemical reactions.