Question

The correct order of energies of molecular orbitals of N2 molecule, is

• A. σ1s<σ1s<σ2s<σ2s<σ2pz<(π2px =π2py)<(π2px=π2py)<σ*2pz
• B. σ1s<σ1s<σ2s<σ2s<σ2pz<σ2pz<(π2px=π2py)<(π2px=π*2py)
• C. σ1s<σ1s<σ2s<σ2s<(π2px=π2py)<(π2px=π2py)<σ2pz<σ*2pz
• D. σ1s<σ1s<σ2s<σ2s<(π2px=π2py)<σ2pz<(π2px=π2py)<σ*2pz

Answer 1

Answer: (D)

σ1s<σ1s<σ2s<σ2s<(π2px=π2py)<σ2pz<(π2px=π2py)<σ*2pz

Answer 2

• The molecular orbitals are arranged in increasing energy levels.
  • The σ1s orbital is the lowest in energy as it is the bonding molecular orbital formed by the overlap of two 1s atomic orbitals.
  • The σ*1s orbital is the next in energy, representing the antibonding orbital formed by the out-of-phase overlap of two 1s atomic orbitals.
  • The σ2s orbital is lower in energy than the σ*2s orbital, as the σ2s is formed by the overlap of two 2s atomic orbitals.
  • The (π2px = π2py) orbitals are degenerate and have the same energy level. These are the bonding and antibonding π molecular orbitals formed by the overlap of two 2px and 2py atomic orbitals.
  • The σ2pz orbital is lower in energy than the (π 2px = π 2py) orbitals, as the σ2pz is formed by the overlap of two 2pz atomic orbitals.
  • Finally, the (π 2px = π 2py) orbitals are the highest in energy among these molecular orbitals.

Therefore, The correct option is (D): σ1s<σ1s<σ2s<σ2s<(π2px=π2py)<σ2pz<(π2px=π2py)<σ*2pz