Question

Describe the properties of O, S, Se, Te and Po (group 16 elements) with reference to thermal stability of hydrides.

Answer 1

The thermal stability of the hydrides of group 16 elements decreases in the order:

H₂O > H₂S > H₂Se > H₂Te

As the centre atom grows in size from H₂O to H₂Te, its propensity to create a stable M-H bond diminishes. When hydrides go from H₂O to H₂Te, their thermal stability declines as the M-H bond gets weaker. H₂S only dissociates at roughly 873 K, while water does so at roughly 2073-2273 K. The existence of hydrogen bonds in water gives it additional stability.