Question

How are the volatilities of the Group 16, and Group 17 hydrides rationalized?

Answer 1

Volatility is a material characteristic in chemistry that defines how easily a substance vaporizes. A material with high volatility is more likely to exist as a vapour at a given temperature and pressure, whereas a substance with low volatility is more likely to exist as a liquid or solid. Volatility also refers to a vapor's ability to condense into a liquid or solid; less volatile compounds will condense from a vapour more quickly than highly volatile ones.

Complete answer:
the volatilities of the Group 16, and Group 17 hydrides are rationalized using mainly two factors
hydrogen bonding
dispersion forces
Water, of course, has the highest degree of hydrogen bonding. As a first-row element, oxygen is considerably more electronegative than sulphur and tellurium, making the OH far more polar. When compared to the lower Group VI hydrides, the resulting intermolecular hydrogen bonding between neighbouring molecules accounts for water's very high boiling point. The Group VII hydrides have the same differential boiling point. Compare the boiling points of HF, HCl, and HBr; the difference is due to hydrogen bonding.
Dispersion forces are the major intermolecular force in the other Group VI hydrides. The temporary polarisation of the electron cloud causes dispersion forces. Because there are more electrons and polarizable electron clouds in bigger atoms and bigger atoms in molecules, there are higher dispersion forces. As a result, ${{H}_{2}}Te$ and ${{H}_{2}}Se$ have the greatest boiling points after water.
It's more difficult to explain why hydrogen sulphide has the lowest boiling point. The hydrogen bonding strength of the ${{H}_{2}}S$ molecule is most likely negligible. The polarity of the H-S bonds is dwarfed by the polarity of the H-O bonds because sulphur is considerably less electronegative than oxygen.
As a result, hydrogen sulphide has the lowest boiling point due to the least amount of intermolecular contact. You're undoubtedly aware that hydrogen sulphide has an unpleasant odour. It's also a highly lethal gas.

Note:
Of course, a little sloppiness next door resulted in the odours of hydrogen sulphide, hydrogen selenide, and hydrogen telluride wafting down the hallway, clearing the floor, and occasionally the entire building. While ${{H}_{2}}S$ has a terrible odour, ${{H}_{2}}Te$ and ${{H}_{2}}Se$ smell like a dead dog; the odour was horrible. These gases were more toxic than hydrogen cyanide, as we discovered later.