question_answer

  Explain the following : (i) Most of the known noble gas compounds are those of xenon. (ii) exists but  does not. (iii) Among the hydrides of elements of group - 16 water shows unusual physical properties.

Answer:

  (i) Due to stable half filled p3 configuration in nitrogen its first ionisation enthalpy is higher than oxygen (p4). (ii) Sulphur vapour exists as  molecule. It exhibits some  paramagnetic behaviour because its anti bonding molecular orbital contains two unpaired electrons. (iii) Ionisation enthalpy of only Xe is lower and suitable or compound formation. (iv) N - N bond is weaker than the single P - P bond because of high interelectronic repulsion of the non bonding electrons owing to the small bond length. As a result catenation tendency is weaker in nitrogen.