Coloured ions formation

• Colour arises when some of the wavelengths of visible light are absorbed and the remaining wavelengths of light are transmitted or reflected.
• Colour arises when some of the wavelengths of visible light are absorbed and the remaining wavelengths of light are transmitted or reflected.
• d electrons move from the ground state to an excited state when light is absorbed.
• The energy difference between the ground state and the excited state of the d electrons is given by:

  ∆E = hν = hc/λ
• Changes in oxidation state, co-ordination number and ligand alter ∆E and this leads to a change in colour.
• The absorption of visible light is used in spectroscopy