question_answer

  (i) Why do the transition elements exhibit higher enthalpies of atomization? (ii) In the series Sc (Z = 21) to Zn (Z = 30) the enthalpy of atomization of zinc is the lowest i.e., 126 kJ . Why?                                                                                                                                                                                              [1+1]

Answer:

  (i) In interatomic metallic bonding (n-1) d electrons in addition to ns electrons are involved. Greater the    number    of    valence    electrons stronger the resultant bonding.    Very high heat of atomisation as all unpaired electrons interatomic bonding. Thus, transition elements exhibit higher enthalpy of atomisation.                                [1] (ii) Zn[Ar]3d10 4s2 All the (n-1) d electrons are paired hence interatomic bonding is least in zinc. Thus, enthalpy of atomisation is also least.     [1]