TheMO diagramofNOis:

The last electron is in fact in the2b1antibonding MO, so the bond order ofNOhas decreased by12relative toNO+orCO.Therefore thebond orderis2.5.

The electronic configuration of carbon and oxygen atom are 1s²2s²2p² and 1s²2s²2p⁴ respectively. There are 4 electrons in the outer shell of carbon and 6 electrons in the outer shell of oxygen. Thus, the total of 10 outer electrons are to be accommodated in the molecular orbitals of CO molecule .Because of higher electronegativity of oxygen, its atomic orbitals would be of lower energy than the corresponding atomic orbitals of carbon .Due to this energy difference, the bonding and antibonding molecular orbitals will receive different contributions from atomic orbitals of carbon and oxygen. The bonding molecular orbitals will receive more contribution from atomic orbitals of lower energy i.e. the atomic orbitals of Oxygen and would be closer to it in energy than the antibonding molecular orbitals which would be closer to carbon in energy.The bonding molecular orbitals would have more characteristics of atomic orbitals of Oxygen and antibonding Molecular orbitals would have more characteristics of carbon.The electronic configuration of CO molecule isσ2s² σ*2s² π2px² π2py² σ2pz²Bond order = 1/2(8–2) = 3Thus ,CO contains a tripple bond. Its bondvdissociation energy is 1067 KJ/mol and bond length is equal to 1.14A⁰.Molecular orbital diagram for CO molecule is gven as.