Question

In an anti-bonding MO the clectron density is minimum (1) around one atom of the molecule (2) between the nuclei (3) at a point away from nuclci of the molecule (4) at no place

Short answer

The electron density is minimum between the nuclei (option 2).

Step-by-step solution

Understand Anti-Bonding Molecular Orbitals (MOs)

Anti-bonding molecular orbitals are formed when atomic orbitals combine with destructive interference, leading to a reduction in electron density between the nuclei of the atoms involved in the bond.

Analyze Electron Density in Anti-Bonding MOs

In anti-bonding MOs, electron density is typically lowest in the region between the nuclei of the bonding atoms. This is due to the destructive interference that creates a node with zero electron density.

Identify the Correct Option

Given the options, the correct choice reflects the concept that the electron density is minimum between the nuclei in an anti-bonding MO.

Key concepts

electron density

Electron density refers to the probability of finding an electron in a specific location around an atom or molecule. It is a key concept in understanding molecular structures and bonding. In a chemical bond, electron density is typically shared between the atoms involved, but its distribution varies based on the type of molecular orbital.
In anti-bonding molecular orbitals, electron density is significantly altered due to specific interactions we're about to explore.

molecular orbitals

Molecular orbitals are regions in a molecule where electrons are likely to be found. They are formed through the combination of atomic orbitals from bonded atoms. There are two main types of molecular orbitals: bonding and anti-bonding.

• Bonding Molecular Orbitals: These are formed when atomic orbitals combine constructively. This means they overlap in a way that increases electron density between the nuclei, stabilizing the molecule.
• Anti-Bonding Molecular Orbitals: Here, atomic orbitals combine through destructive interference. This leads to a node where electron density is zero, typically between the nuclei of the atoms. These orbitals can often destabilize the molecule as a result.

The behavior of electrons in these orbitals explains many chemical properties and reactions.

destructive interference

Destructive interference occurs when two waves combine in such a way that they cancel each other out. In the context of molecular orbitals, this happens when electron waves from atomic orbitals overlap destructively.
In anti-bonding molecular orbitals, destructive interference leads to a reduction in electron density between the nuclei. This is why electron density is lowest at the node in these orbitals.
Understanding this concept helps to explain why anti-bonding orbitals are higher in energy compared to bonding orbitals. This higher energy state is less stable, which is why electrons tend to preferentially fill bonding orbitals first.