Chapter 20, Problem 7RQ

Interpretation Introduction

Interpretation: The reason for the crystal field model predicting the magnetic properties of the complex ions and the colors of the complex ions; the reason for the yellow color of $\text{Cr}{\left({\text{NH}}_{\text{3}}\right)}^{3+}$ by not absorbing the yellow color; the meaning of the spectrochemical series and the reason for development of the spectrochemical series by the study of light absorbed by different complex ions; and comparison of the wavelength absorbed by $\text{Co}{\left({\text{NH}}_{\text{3}}\right)}^{2+}$ with that by $\text{Co}{\left({\text{NH}}_{\text{3}}\right)}^{3+}$ is to be stated.

Concept introduction: If the electrons in the hybridized orbital are all paired, the magnetic property of each electron is nullified by the magnetic field of its pair. Thus, the complex is repelled by the magnetic field and the complex is said to exhibit diamagnetism.

Coordination complex exhibits coloration due to $\text{d}-\text{d}$ transition of electrons.

The spectrochemical series is the series of the ligand arranged in the decreasing order of their ability to split the crystal field and absorb the equivalent energy for $\text{d}-\text{d}$ transition.

Ligands are the electron donating group, therefore, are attracted by the positively charged transition metal. Thus, more the oxidation number of a metal ion, more will be the strength of attraction of ligand and more will be the crystal field energy gap created by the ligand.

To determine: The reason for the crystal field model predicting the magnetic properties of the complex ions and the colors of the complex ions; the reason for the yellow color of $\text{Cr}{\left({\text{NH}}_{\text{3}}\right)}^{3+}$ by not absorbing the yellow color; the meaning of the spectrocheminal series and the reason for development of the spectrochemical series by the study of light absorbed by different complex ions; and comparison of the wavelength absorbed by $\text{Co}{\left({\text{NH}}_{\text{3}}\right)}^{2+}$ with that by $\text{Co}{\left({\text{NH}}_{\text{3}}\right)}^{3+}$.