--- title: "Crystal Field Theory and the Splitting of d Orbitals" description: "Bringing charged or polar ligands up to a metal ion raises some d orbitals more than others. The size of that split explains the colour of a complex, its magnetism and part of its stability." canonical: https://lightmysky.com/learn/science/crystal-field-theory-and-the-splitting-of-d-orbitals-mt_YfIBGXj8su source: https://lightmysky.com/learn/science/crystal-field-theory-and-the-splitting-of-d-orbitals-mt_YfIBGXj8su.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Crystal Field Theory and the Splitting of d Orbitals Bringing charged or polar ligands up to a metal ion raises some d orbitals more than others. The size of that split explains the colour of a complex, its magnetism and part of its stability. Subject: Science · Area: Chemistry · Ages 19 to 20 Page: https://lightmysky.com/learn/science/crystal-field-theory-and-the-splitting-of-d-orbitals-mt_YfIBGXj8su ## Ready when they can - Explains why the two sets of d orbitals separate in an octahedral field, from the direction each orbital points - Draws the splitting pattern for octahedral, tetrahedral and square planar fields and compares the gap sizes - Calculates crystal field stabilisation energy for a stated configuration - Links the gap to the wavelength absorbed and so to the colour observed ## Lesson: Why complexes have colour Bring six ligands up along the axes and the five d orbitals stop being equal. The two orbitals aimed straight at the ligands meet their charge head on and climb in energy, while the three aimed between the axes relax downward. The gap between the upper pair and the lower trio is the splitting energy, and everything about colour and magnetism flows from it. Other geometries reshuffle the same deck. Tetrahedral ligands slip between the axes, so the pattern flips upside down and shrinks to less than half the octahedral gap. Square planar geometry spreads the five orbitals into four distinct rungs with a huge top step. Always fix the metal oxidation state first, since it sets the d count that must fill these levels one electron per level before pairing. **Example.** Stabilisation energy is just bookkeeping: count minus 0.4 of the gap per lower electron and plus 0.6 per upper one. A high spin d6 ion holds four electrons below and two above, giving minus 1.6 plus 1.2, which is minus 0.4 of the gap. That same d6 ion carries four unpaired electrons, since only one of its six electrons has found a partner. **Tip.** Colour is the gap made visible. The complex swallows the light whose packet matches the gap, and your eye receives the rest, so a yellow solution is one that ate violet and blue. A bigger gap eats shorter wavelength light: strong field ligands widen the gap toward the blue end, and the colour you see shifts the other way. **Recap.** Ligands split the d orbitals by direction, electron counts set the stabilisation, and the gap decides which colour is absorbed. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Coordination Compounds: Naming, Geometry and Isomerism](https://lightmysky.com/learn/science/coordination-compounds-naming-geometry-and-isomerism-mt_rkHM3jL3Ri) - [Transition Metals: Variable Oxidation State, Colour and Catalysis](https://lightmysky.com/learn/science/transition-metals-variable-oxidation-state-colour-and-catalysis-mt_UIVC6d7wak) ## Opens up - [The Spectrochemical Series, Spin State and Magnetism](https://lightmysky.com/learn/science/the-spectrochemical-series-spin-state-and-magnetism-mt_gfKL7W8kg-)