Super admin . 5th Jul, 2025 4:52 PM
One of the most fascinating features of transition metal compounds is their vibrant and varied colors. From the deep blue of copper(II) sulfate to the bright purple of potassium permanganate, these striking hues come from the unique chemistry of transition metals.
The secret lies in the arrangement of electrons in the d-orbitals of transition metal ions. In an isolated metal ion, the five d-orbitals have the same energy. However, when ligands like water, ammonia, or chloride surround the metal ion in a coordination complex, they interact with these orbitals, causing them to split into two energy levels — a phenomenon known as crystal field splitting.
When white light passes through a solution of a transition metal compound, certain wavelengths of light are absorbed to promote electrons from the lower energy d-orbital to the higher one. The specific wavelength absorbed depends on factors like the type of metal, its oxidation state, the arrangement of ligands, and the strength of the metal-ligand bonds. The color we perceive is the combination of wavelengths that are transmitted or reflected.
This principle not only explains the beautiful colors in metal compounds but also plays a crucial role in applications like pigments, dyes, and analytical chemistry.