Complete the exercises below. Draw the crystal-field energy-level diagrams and show the placement of d electrons for each of the following: a. [Cr(H₂O)₆]²⁺ (four unpaired electrons).

Crystal Field Theory (CFT) explains how the arrangement of ligands around a central metal ion affects the energy levels of its d orbitals. In an octahedral complex like [Cr(H₂O)₆]²⁺, the d orbitals split into two energy levels: the lower-energy t₂g and the higher-energy e_g orbitals. This splitting is crucial for understanding the electronic configuration and magnetic properties of the complex.

The electron configuration of an atom describes the distribution of electrons among the various atomic orbitals. For transition metals, this involves the d orbitals, which can hold up to ten electrons. In the case of [Cr(H₂O)₆]²⁺, chromium loses two electrons from its 3d orbitals, resulting in a configuration that influences the number of unpaired electrons and the overall magnetic behavior of the complex.

Ligand field strength refers to the ability of ligands to influence the energy levels of the d orbitals in a metal complex. Strong field ligands, like CN⁻, cause a larger splitting of the d orbitals, while weak field ligands, like H₂O, result in smaller splitting. The nature of the ligands affects the number of unpaired electrons and the magnetic properties of the complex, which is essential for drawing the correct energy-level diagram.