The correct order of configuration of O2 molecule according to MOT is

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AIIMS BSc NURSING 2023 Memory-Based Paper

\(\begin{array}{l} \sigma \mathrm{s}^{2}<\sigma^{*} 1 \mathrm{~s}^{2}<\sigma 2 \mathrm{~s}^{2}<\sigma^{*} 2 \mathrm{~s}^{2}<\left(\pi 2 \mathrm{p}_{\mathrm{x}}^{2}=\pi 2 \mathrm{p}_{\mathrm{y}}^{2}\right) <\sigma 2 \mathrm{p}_{\mathrm{z}}^{2}<\left(\pi^{*} 2 \mathrm{p}_{\mathrm{x}}^{1}=\pi^{*} 2 \mathrm{p}_{\mathrm{y}}^{1}\right) \end{array}\)
\(\begin{array}{l} \sigma 1 s^{2}<\sigma^{*} 1 s^{2}<\sigma 2 s^{2}<\sigma * 2 s^{2}<\sigma 2 p_{z}^{2}< \left(\pi 2 p_{x}^{2}=\pi 2 \mathrm{p}_{\mathrm{y}}^{2}\right)<\left(\pi^{*} 2 \mathrm{p}_{\mathrm{x}}^{1}=\pi^{*} 2 \mathrm{p}_{\mathrm{y}}^{1}\right) \end{array}\)
\(\begin{array}{l} \sigma 1 s^{2}<\sigma^{*} 1 s^{2}<\sigma 2 s^{2}<\left(\pi 2 p^{2}=\pi 2 p_{y}^{2}\right) <\left(\pi^{*} 2 p_{x}^{2}=\pi^{*} 2 p_{y}^{2}\right)<\sigma^{*} 2 s^{2} \end{array}\)
\(\begin{array}{l} \sigma 1 s^{2}<\sigma * 1 s^{2}<\sigma 2 s^{2}<\sigma * 2 s^{2}<\left(\pi 2 p_{x}^{2}=\pi 2 p_{y}^{2}\right) <\left(\pi^{*} 2 p_{x}^{2}=\pi^{*} 2 p_{y}^{2}\right) \end{array}\)

Answer 1

CONCEPT:

Molecular Orbital Theory (MOT) for O₂ Molecule

Molecular Orbital Theory (MOT) explains the bonding in molecules by combining atomic orbitals to form molecular orbitals, which are spread over the entire molecule.
In O₂, the molecular orbitals are formed by the combination of atomic orbitals from two oxygen atoms.
The molecular orbitals are filled according to the Aufbau principle, Pauli exclusion principle, and Hund's rule.

EXPLANATION:

The correct order of filling molecular orbitals for O₂ molecule is as follows:
- σ 1s²: The bonding molecular orbital formed by the combination of 1s orbitals from both oxygen atoms.
- σ* 1s²: The antibonding molecular orbital formed by the combination of 1s orbitals from both oxygen atoms.
- σ 2s²: The bonding molecular orbital formed by the combination of 2s orbitals from both oxygen atoms.
- σ* 2s²: The antibonding molecular orbital formed by the combination of 2s orbitals from both oxygen atoms.
- σ 2p_z²: The bonding molecular orbital formed by the combination of 2p_z orbitals from both oxygen atoms.
- π 2p_x² = π 2p_y²: The degenerate bonding molecular orbitals formed by the combination of 2p_x and 2p_y orbitals from both oxygen atoms.
- π* 2p_x¹ = π* 2p_y¹: The degenerate antibonding molecular orbitals formed by the combination of 2p_x and 2p_y orbitals from both oxygen atoms.
Based on this order, the correct configuration of the O₂ molecule is:
σ 1s² < σ* 1s² < σ 2s² < σ* 2s² < σ 2p_z² < (π 2p_x² = π 2p_y²) < (π* 2p_x¹ = π* 2p_y¹)

Therefore, the correct order of configuration of O₂ molecule according to MOT is Option 2.