What is the bond order of the O–O bond in molecular oxygen (O_2)?

• A. 1
• B. 2
• C. 2.5
• D. 3

Answer: (B)

Verified step by step guidance

1. Recall that bond order is defined as half the difference between the number of bonding electrons and antibonding electrons: \(\text{Bond order} = \frac{\text{Number of bonding electrons} - \text{Number of antibonding electrons}}{2}\).
2. Write the electron configuration of molecular oxygen (O\_2) using molecular orbital theory. Oxygen has 16 electrons total, so fill the molecular orbitals in order: \(\sigma_{2s}\), \(\sigma^*_{2s}\), \(\sigma_{2p_z}\), \(\pi_{2p_x}\) and \(\pi_{2p_y}\), then \(\pi^*_{2p_x}\) and \(\pi^*_{2p_y}\).
3. Count the number of electrons in bonding orbitals and antibonding orbitals based on the molecular orbital diagram for O\_2. Bonding orbitals include \(\sigma_{2s}\), \(\sigma_{2p_z}\), and \(\pi_{2p_x}\)/\(\pi_{2p_y}\); antibonding orbitals include \(\sigma^*_{2s}\) and \(\pi^*_{2p_x}\)/\(\pi^*_{2p_y}\).
4. Calculate the bond order by substituting the number of bonding and antibonding electrons into the bond order formula.
5. Interpret the bond order value to understand the strength and stability of the O–O bond in O\_2.