Question

The pairs of species of oxygen and their magnetic behaviours are noted below. Which of the following presents the correct description ?

• A. $O , O^{2-}_2$ - Both paramagnetic
• B. $O^-_2 , O^{2-}_2$ - Both diamagnetic
• C. $O^+ , O^{2-}_2$ - Both paramagnetic
• D. $O^+_2 , O_2$ - Both paramagnetic

Answer 1

The Correct Option is D

The question asks about the magnetic behavior of given oxygen species pairs and requires identifying the option with the correct description.

To determine the magnetic behavior, we need to analyze the electron configuration and molecular orbital theory for the given oxygen species.

1. Understanding Magnetic Properties:
   • Paramagnetic: Species with unpaired electrons.
   • Diamagnetic: Species with all paired electrons.
2. Analysis of the given options:
   1. Option 1: O_2 and O^{2-}_2 are mentioned to be both paramagnetic.
   2. Option 2: O^-_2 and O^{2-}_2 are mentioned to be both diamagnetic.
   3. Option 3: O^+_2 and O^{2-}_2 are mentioned to be both paramagnetic.
   4. Option 4: O^+_2 and O_2 are mentioned to be both paramagnetic.
3. Electron configuration using Molecular Orbital (MO) theory:
   • O_2: Has a configuration of \sigma 1s^2, \sigma^* 1s^2, \sigma 2s^2, \sigma^* 2s^2, \sigma 2p_z^2, \pi 2p_x^2 = \pi 2p_y^2, \pi^* 2p_x^1 = \pi^* 2p_y^1. It has two unpaired electrons, making it paramagnetic.
   • O^{2-}_2: Receives two additional electrons. Additional configuration becomes \pi^* 2p_x^2 = \pi^* 2p_y^2. There are no unpaired electrons, making it diamagnetic.
   • O^+_2: Loses one electron from \pi^* 2p orbitals. At least one electron remains unpaired, so it is paramagnetic.
   • O^-_2: Gains an extra electron, but the presence in \pi^* 2p ensures unpaired electrons, so it remains paramagnetic.

Based on the MO theory analysis, the correct description is as follows:

Option 4: O^+_2 and O_2 - Both paramagnetic. This is the correct option since both species have unpaired electrons.