Discuss the trends in chemical reactivity of group 15 elements.
General trends in chemical properties of group − 15(i) Reactivity towards hydrogen: The elements of group 15 react with hydrogen to form hydrides of type EH3 , where E = N, P, As, Sb, or Bi. The stability of hydrides decreases on moving down from NH3 to BiH3.(ii) Reactivity towards oxygen: The elements of group 15 form two types of oxides: E2O3 and E2O5 , where E = N, P, As, Sb, or Bi. The oxide with the element in the higher oxidation state is more acidic than the other. However, the acidic character decreases on moving down a group.(iii) Reactivity towards halogens: The group 15 elements react with halogens to form two series of salts: EX3 and EX5 . However, nitrogen does not form NX5 as it lacks the d-orbital. All trihalides (except NX3 ) are stable.(iv) Reactivity towards metals: The group 15 elements react with metals to form binary compounds in which metals exhibit −3 oxidation states.