Q.What is crystal field splitting energy?

Step 1. In an isolated gaseous metal ion, all five d orbitals are degenerate (equal energy).

Step 2. When ligands approach the metal along their real, directional bond axes (rather than uniformly from a spherical field), orbitals pointing toward the ligands are repelled more strongly than orbitals pointing away from or between the ligands.

Step 3. This unequal repulsion splits the five d orbitals into two (or more) sets at different energies -- in an octahedral field, the higher-energy eg set (dz², dx²-y²) and the lower-energy t2g set (dxy, dyz, dxz); in a tetrahedral field, the pattern inverts.

Step 4. The crystal field splitting energy, given the symbol Δ₀ for an octahedral field (or Δt for a tetrahedral field), is defined as the total energy gap between these split sets of orbitals. …

Define Δ as the energy gap between the split d-orbital sets that arises from the DIRECTIONAL approach of ligands (not from the earlier, uniform 's …

• Defining Δ as just 'the energy of the d orbitals' rather than specifically the GAP/difference between the two split sets. …