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?

Explanation

In the formation of metallic bonds, no eletrons from 3d-orbitals are involved
in case of zinc, while in all other metals of the 3d series, electrons from
the d-orbitals are always involved in the formation of metallic bonds.