Using the molecular orbital energy ordering for second-row homonuclear diatomic molecules in which the π2p orbitals lie at higher energy than the σ2p, draw MO energy diagrams and predict the bond order in a molecule or ion with 12 total valence electrons. Will the molecule or ion be diamagnetic or paramagnetic?

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1. Identify the second-row homonuclear diatomic molecule or ion with 12 valence electrons. Examples include \( \text{C}_2 \) or \( \text{N}_2^+ \).
2. Write the electron configuration for the molecule using the molecular orbital (MO) theory. For second-row diatomic molecules, the order is: \( \sigma_{1s}^2, \sigma^*_{1s}^2, \sigma_{2s}^2, \sigma^*_{2s}^2, \pi_{2p_x}^2 = \pi_{2p_y}^2, \sigma_{2p_z}^2 \).
3. Fill the molecular orbitals with the 12 valence electrons according to the Aufbau principle, Pauli exclusion principle, and Hund's rule.
4. Calculate the bond order using the formula: \( \text{Bond Order} = \frac{1}{2}[(\text{Number of electrons in bonding MOs}) - (\text{Number of electrons in antibonding MOs})] \).
5. Determine if the molecule or ion is diamagnetic or paramagnetic by checking for unpaired electrons in the molecular orbitals. If all electrons are paired, it is diamagnetic; if there are unpaired electrons, it is paramagnetic.