p Block Elements Part 1

The H−X bond strength decreases from HF to HI. i.e. HF>HCl>HBr>HI. Thus HF is most stable while HI is least stable. This is evident from their decompositions reaction: HF and HCl are stable upto 1473K,HBr decreases slightly and HI dissociates considerably 713K. The decreasing stability of the hydrogen halide is also reflected in the values of dissociation energy of the H−X bond