Chapter 20, Problem 20.25QP

Interpretation Introduction

Interpretation: The compound of ${\text{Sc}}^{\text{3+}}$ is colorless but ${\text{Ti}}^{\text{3+}}$ is colored, the reason to be explained.

Concept Introduction:

Crystal field theory: Bonding in coordination compounds accounts for the magnetic property and color of the complex ion. Crystal field theory is explained in terms of electrostatic interaction of between metal ion and ligands.

Crystal field splitting: The energy gap between the splitting of d-orbitals of the metal ion in presence of ligands is known as the crystal field splitting $\text{(Δ)}$. The magnitude of $\text{(Δ)}$ is depends on the nature of metal ions and the ligands.

Origin of color: The coordination compound exhibit color due to d-d transitions. Absorption of wavelength from visible region which excites electron from the lower energy level to the higher energy level transmits the complementary color. Thus, the coordination compound looks colored.