Question

What is crystal field splitting energy?

Answer 1

The energy used in the splitting of degenerate d-orbitals due to the presence of ligands in a definite geometry is called Crystal Field Splitting Energy.
Step 1: Understanding Crystal Field Splitting Energy When ligands approach a transition metal ion, the degeneracy of the d-orbitals is lifted due to electrostatic interactions, causing them to split into two sets of orbitals: \[ t_{2g} \quad \text{(lower energy)} \quad \text{and} \quad e_g \quad \text{(higher energy)} \] The energy difference between these orbitals is called Crystal Field Splitting Energy (\(\Delta\)).

Answer 2

The violet colour arises due to the d-d electronic transition within the split d-orbitals.
Step 1: Electronic Configuration of \( [\text{Ti(H}_2\text{O)_6]^{3+} \)} For \( \text{Ti}^{3+} \), the electronic configuration is: \[ \text{Ti}^{3+} = 3d^1 \] Step 2: Crystal Field Splitting and d-d Transition In an octahedral field, the d-orbitals split into: \[ t_{2g} \quad \text{(lower energy)} \quad \text{and} \quad e_g \quad \text{(higher energy)} \] Since Ti\(^{3+}\) has one electron, it occupies the \( t_{2g} \) orbital as: \[ t_{2g}^1 e_g^0 \] Step 3: Cause of Violet Colour When visible light is absorbed, the electron gets excited from the \( t_{2g} \) to the \( e_g \) orbital, causing a d-d transition. The observed colour (violet) is due to the complementary colour of the absorbed wavelength.

Answer 3

\( [\text{Cr(NH}_3)_6]^{3+} \) is paramagnetic due to unpaired electrons, while \( [\text{Ni(CN)}_4]^{2-} \) is diamagnetic due to electron pairing.
Step 1: Electronic Configuration of Cr\(^{3+}\) and Ni\(^{2+}\) \[ \text{Cr}^{3+} = 3d^3, \quad \text{Ni}^{2+} = 3d^8 \] Step 2: Effect of Ligands on Magnetic Properties - \( NH_3 \) is a weak field ligand, so it does not cause electron pairing in \( [\text{Cr(NH}_3)_6]^{3+} \), leaving unpaired electrons in the \( t_{2g} \) orbitals. - \( CN^- \) is a strong field ligand, so it pairs electrons in \( [\text{Ni(CN)}_4]^{2-} \), making it diamagnetic.

Answer 4

Step 1: Electronic Configuration of Fe\(^{3+}\) \[ \text{Fe}^{3+} = 3d^5 \] Step 2: Effect of Ligands on Hybridization - \( CN^- \) is a strong field ligand, causing electron pairing and leading to \( d^2sp^3 \) hybridization (inner orbital complex). - \( H_2O \) is a weak field ligand, preventing electron pairing and leading to \( sp^3d^2 \) hybridization (outer orbital complex).