Multiple Choice
Which of the following correctly describes the molecular orbital energy diagram for the diatomic molecule He_2?
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12. Molecular Shapes & Valence Bond Theory
Molecular Orbital Theory
Multiple Choice
Using a molecular orbital (MO) diagram, calculate the bond order for O_2.
A
1
B
0
C
2
D
3
Verified step by step guidance1
Identify the total number of valence electrons in the O_2 molecule. Each oxygen atom has 6 valence electrons, so for O_2, the total is \(6 \times 2 = 12\) electrons.
Draw the molecular orbital (MO) diagram for O_2, placing the molecular orbitals in the correct energy order. For O_2, the order of orbitals from lowest to highest energy is: \(\sigma_{2s}\), \(\sigma_{2s}^*\), \(\sigma_{2p_z}\), \(\pi_{2p_x} = \pi_{2p_y}\), \(\pi_{2p_x}^* = \pi_{2p_y}^*\), and \(\sigma_{2p_z}^*\).
Fill the molecular orbitals with the 12 valence electrons following the Aufbau principle, Pauli exclusion principle, and Hund's rule. Start filling from the lowest energy orbital and move upwards, placing electrons in degenerate orbitals singly before pairing.
Count the number of electrons in bonding orbitals and antibonding orbitals separately. Bonding orbitals stabilize the molecule, while antibonding orbitals destabilize it.
Calculate the bond order using the formula: \(\text{Bond order} = \frac{(\text{number of electrons in bonding orbitals}) - (\text{number of electrons in antibonding orbitals})}{2}\). This value indicates the strength and stability of the bond.
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