Question

Which of the following best describes the diagram below of a molecular orbital ?

• A. A non-bonding orbital
• B. An antibonding $\sigma$ orbital
• C. A bonding $\pi$ orbital
• D. An antibonding $\pi$ orbital

Answer 1

The Correct Option is D

To determine which option best describes the molecular orbital (MO) depicted in the unseen diagram, let's consider the characteristics of different types of molecular orbitals.

1. **Bonding Orbital:** These orbitals arise from the constructive interference of atomic orbitals, leading to a decrease in energy compared to the separated atoms. They have electron density concentrated between the nuclei, which helps hold the atoms together.

2. **Antibonding Orbital:** In contrast, antibonding orbitals result from destructive interference, increasing the energy and generally having a node between the nuclei where electron density is zero.

3. **Non-bonding Orbital:** These orbitals do not partake in bonding. Their energy levels are similar to the original atomic orbitals since they neither benefit from constructive interference nor suffer from destructive interference.

4. **Types of Orbitals:** - **Sigma (σ) Orbital:** Formed by the end-to-end overlap of atomic orbitals, usually s-s, p-p, or p-d orbitals. - **Pi (π) Orbital:** Formed by the side-by-side overlap of p orbitals, characteristic of bonds in double and triple bonds.

Given the correct answer is an antibonding $\pi$ orbital, the diagram likely shows a molecular orbital with a node between the nuclei, and it involves p orbitals overlapping laterally.

5. **Conclusion:** The presence of a node (as seen in antibonding orbitals) and the type of lateral overlap (indicative of π orbitals) confirms the depiction as an antibonding $\pi$ orbital.

Therefore, the best description for the molecular orbital diagram is: An antibonding $\pi$ orbital.