question_answer

\[Z{{n}^{2+}}\] salts are white while \[C{{u}^{2+}}\] salts are blue. Explain.

Answer:

                  The \[Z{{n}^{2+}}\] ion has all filled orbitals whereas \[C{{u}^{2+}}\] ion (\[3{{d}^{9}}\] configuration) has one half filled 3d-orbital. It has therefore, a tendency to form coloured ion in solution whereas \[Z{{n}^{2+}}\] has no such tendency. Thus, \[Z{{n}^{2+}}\] salts are white while those of \[C{{u}^{2+}}\] are blue.