In the interactive display below, the 3s orbital for the left atom and the 3py orbital for the right atom are shown. Use the controls to move the orbitals close to each other and carefully observe the overlap of the two orbitals.
In this example, overlap occurs in two regions.
In the lower overlap region, the 3s orbital (positive wave function sign) overlaps with the positive region of the 3py orbital. This overlap produces a constructive interaction between the orbitals.
In the upper overlap region, the 3s orbital (positive wave function sign) overlaps with the negative region of the 3py orbital. This overlap produces a destructive interaction between the orbitals.
The symmetry of the two orbitals is such that the degree of constructive interaction in the lower region is exactly cancelled by the destructive interaction in the upper region. Consequently, there is no net interaction between the 3s and 3py orbitals and the orbitals, in this example, are nonbonding.
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