Construct the molecular orbital diagram for N2

Construct the molecular orbital diagram for N2.

The Correct Answer and Explanation is:

To construct the molecular orbital diagram for nitrogen (N₂), we first need to understand the basic principles of molecular orbitals (MOs). The diagram represents the combination of atomic orbitals (AOs) from two nitrogen atoms, and it shows the energy levels of the molecular orbitals formed.

Steps for constructing the molecular orbital diagram of N₂:

1. Atomic Orbitals:
   Each nitrogen atom has the following electron configuration: 1s² 2s² 2p³. The valence electrons (in the 2s and 2p orbitals) will be involved in bonding and antibonding interactions.
2. Molecular Orbitals (MOs):
   The atomic orbitals combine to form molecular orbitals. The s orbitals combine to form a bonding σ(2s) and an antibonding σ*(2s). Similarly, the p orbitals combine in different ways:
   • Bonding MOs: σ(2p) and π(2p)
   • Antibonding MOs: σ*(2p) and π*(2p)
   The energy order of MOs for molecules with fewer than 8 electrons in the p orbitals (like N₂) follows this pattern:
   • σ(2s) < σ*(2s) < σ(2p) < π(2p) < π*(2p) < σ*(2p)
3. Electron Configuration:
   Nitrogen has 10 valence electrons, which we place in the molecular orbitals as follows:
   • The first two electrons go into the bonding σ(2s) orbital.
   • The next two electrons go into the antibonding σ*(2s) orbital.
   • The next two electrons go into the bonding σ(2p) orbital.
   • The remaining four electrons will be placed in the degenerate π(2p) orbitals, two electrons in each.
4. Bond Order Calculation:
   The bond order is calculated by the formula: Bond Order=Number of electrons in bonding orbitals−Number of electrons in antibonding orbitals2\text{Bond Order} = \frac{\text{Number of electrons in bonding orbitals} – \text{Number of electrons in antibonding orbitals}}{2}Bond Order=2Number of electrons in bonding orbitals−Number of electrons in antibonding orbitals​ For N₂:
   • Bonding electrons: 2 (σ(2s)) + 2 (σ(2p)) + 4 (π(2p)) = 8
   • Antibonding electrons: 2 (σ*(2s))
     Bond order = (8 – 2) / 2 = 3

Thus, N₂ has a bond order of 3, indicating a triple bond between the two nitrogen atoms.

Conclusion:

The molecular orbital diagram for N₂ consists of six molecular orbitals: σ(2s), σ*(2s), σ(2p), π(2p), π*(2p), and σ*(2p). The electron configuration places electrons in these orbitals in a way that gives N₂ a triple bond, which is consistent with the observed properties of the molecule.