Crystal Field Theory and the Splitting of d Orbitals · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Why complexes have colour

Science · Chemistry · ages 19-20
Name ______________________   Date ____________

  1. How does the tetrahedral splitting gap compare with the octahedral one?

    • Much bigger, more than double
    • Inverted and less than half the size
    • Exactly equal but reversed

  2. Why do d orbitals split into two sets in an octahedral field?

    • Two orbitals point at the ligands and rise, three point between and sink
    • The ligands spin around the metal
    • The metal loses all its d electrons

  3. A complex shows the colour left over after it absorbs the light matching its gap.

    Circle one:   True   False

  4. A high spin d6 ion fills each level singly before pairing. Type its number of unpaired electrons.

    Answer: ______________

  5. A high spin d6 ion has four lower and two upper electrons. Type its stabilisation in gap units.

    Answer: ______________

  6. A stronger field ligand widens the gap. Which light gets absorbed now?

    • Longer wavelength light
    • Shorter wavelength light
    • Sound waves

  7. Tetrahedral complexes are usually low spin because their gap is tiny.

    Circle one:   True   False

  8. Two octahedral complexes share one metal but carry different ligands. Which absorbs at longer wavelength?

    • The one with the strong field ligand
    • Both absorb identically
    • The one with the weak field ligand
LightMySky · lightmysky.comW1-mt_YfIBGXj8su-s1

Answer key

For grown-ups. Fold this page away before handing over the rest.

Why complexes have colour W1-mt_YfIBGXj8su-s1

  1. Inverted and less than half the size · Tetrahedral ligands dodge the axes, so the split flips and shrinks.
  2. Two orbitals point at the ligands and rise, three point between and sink · Direction decides energy: head-on orbitals cost more.
  3. True · Absorbed light is removed, so the eye receives the rest.
  4. 4 · Six electrons with one pair leave four unpaired.
  5. -0.4 · Four times minus 0.4 plus two times plus 0.6 equals minus 0.4.
  6. Shorter wavelength light · Bigger gaps match more energetic, shorter wavelength packets.
  7. False · A tiny gap never repays pairing, so tetrahedral complexes stay high spin.
  8. The one with the weak field ligand · Weak field means a smaller gap, which matches longer wavelength light.
Worksheet · LightMySky