Q. Show Bond Lengths and pΠ - dΠ bonding?

The bonds between S and 0 are much shorter than expected for a single bond in its oxides and therefore, may be considered as double bonds. Along with a sigma bond between S and 0, a ?-bond is also formed by overlap of oxygen p-orbital and sulphur d -orbital forming a pΠ - dΠ bond. Oxygen and sulphur have comparable energy and the size of p and d orbitals and, therefore, have effective pΠ - dΠ overlap. But going from Se to Te, weaker bonds are formed because of difference in the size and energy of the p and d orbitals.