Consider the gaseous ions $ ext{Mn}^{3+}$, $ ext{Cr}^{3+}$, $ ext{V}^{3+}$, and $ ext{Ti}^{3+}$.

Question

Consider the gaseous ions $	ext{Mn}^{3+}$, $	ext{Cr}^{3+}$, $	ext{V}^{3+}$, and $	ext{Ti}^{3+}$. Which of these ions is the most stable in an aqueous solution and why?

Professor PC Thomas Classes · Answer

In an aqueous solution (octahedral field), the d-orbitals split into $t_{2g}$ and $e_g$ levels. $	ext{Cr}^{3+}$ has a $3d^3$ configuration, meaning it has a completely half-filled $t_{2g}^3$ level. This provides high crystal field stabilization energy, making it exceptionally stable.