A) Explain How the Crystal Field Theory Can Use the Magnitude

Essay

A) Explain how the crystal field theory can use the magnitude of the splitting energy $\Delta$ to provide an explanation of the color and magnetic properties of octahedral complexes.
B) In promoting an electron from the t_2g set of orbitals to the e_g set, an octahedral complex absorbs a photon with a wavelength $\lambda$ of 523 nm. Calculate the value of $\Delta$ in the complex, in kJ/mol.