Heteronuclear diatomic molecule

Because the electronegativity and effective nuclear charge of the two elements are different, the energy of the atomic orbitals in the same layer is different
.
For example, the energy of the atomic orbital of the C atom in the same layer is higher than that of the O atom, and the energy of the 1s orbital of the H atom is higher than the energy of the 2p orbital of the F atom

1) CO molecule

FIG molecular orbital level of CO (FIG.
6-27) similar to the N2 molecule [FIG.
6-23 (a)], [sigma] bonding orbital _2P energy than [pi] _2P higher
.
The molecular orbital formula of CO is KK(σ _2s ) ² (σ* _2s ) ² (π2 _py ) ² (π2 _pz )2(σ2 _px ) ² , the bond level of the molecule is 3, with 1 σ bond and 2 π bonds

The energy diagram of NO molecular orbital is similar to that of O ₂
.
The bond level of NO molecule is 2.

2) HF molecule

Since the energy of the H atom's 1s orbital is higher than the energy of the F atom's 2p orbital, the H atom's 1s orbital and the F atom's 2p orbital have similar energy and can be combined into effective molecular orbitals (Figure 6-28)
.

Figure 6-27 Energy level diagram and electron arrangement of CO molecular orbital

Figure 6-28 HF molecular orbital energy level diagram and electron arrangement

When the H atom and the F atom approach along the x-axis, the 1s orbital of the H atom has the same symmetry as the 2 _px orbital of the F atom , which is combined into a bonding orbital 3σ and an antibonding orbital 4σ; 2 _py and 2 _{pz of the} F atom are related to The 1s orbital symmetry of the H atom is different.
The energy in the molecular orbital (1π and 2π) is the same as in the atomic orbital, and has no effect on the bond level of the HF molecule, so it is called a non-bonded orbital

Related Links: Homonuclear Diatomic Molecules