Test: Group-16 Elements - NEET

Group 16 elements have a lower value of first ionization enthalpy as compared to group 15 elements. As group 15 elements have half filled p-orbital due to which group 15 have got extra stability.

Oxygen does not have a d-orbital thereby not exceeding its covalency beyond 2. Whereas sulphur has vacant d-orbitals hence can exceed its covalency to +4 or +6.

The difference in the bond angles is linked with the electronegativities of oxygen and sulphur atoms. As we move down the group from O to Te, the size of the central atom goes on increasing and its electronegativity goes on decreasing. 
As a result, the position of the two bond pairs shifts away and away from the central atom as we move from H₂​O to H_2​Te. Consequently, the repulsion between the bond pairs decreases as we move from H₂​O to H₂​Te and therefore, the bond angle decreases in the order.

There is a decrease in bond enthalpy (H- E) the size of the element increases on moving down the group hence, the stability decreases on moving down group.