The d– & f- block elements 5 Sample Paper with Answer Sheet

In Cr the electronic configuration is 3d5 4s1 and for Cu, it is 3d10 4s1. In these after first ionization, which removes the electron from 4s , second ionization requires disturbance in half filled or fully filled configuration which requires high enthalpy whereas the configuration of Zn is 3d104s2. Here after second ionization, the configuration of Zn is completely filled. Therefore second ionization is easier for Zn but difficult for Cr and Cu.