question_answer 2)

  In the series Sc (Z = 21) to Zn (Z = 30), the enthalpy of atomisation of zinc is the lowest i.e. 126 kJ mol–1. Why?

Answer:

Zinc (4d10 5s2) has completely filled d-orbital and has no unpaired electron to take part in the formation of metallic bonds. On the other hand, all the other elements in the transition series have one or more unpaired electrons and can participate in the formation of these bonds. As a result, the metallic bonding in zinc is weakest and it has least enthalpy of atomisation.