// CHEMISTRY L5 — TRANSITION METALS
The colourful middle of the table.
The d-block metals break all the tidy rules: many oxidation states, brilliantly coloured compounds, and a genius for catalysis. Tap an ion and see the colour its solution actually turns.
// FIG. 01 — THE ION COLOUR BENCH
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OX STATE {{ oxState }}
COLOUR: {{ colourName }}
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Colour comes from d-electrons absorbing part of the visible spectrum; we see the colours that are left.
// WHAT MAKES A TRANSITION METAL
Transition metals are d-block elements that form at least one ion with a partially filled d-subshell. That half-empty d-shell is behind nearly all their special behaviour. They're typically hard, dense, high-melting metals — a world away from the soft, low-melting Group-1 metals.
// FOUR SIGNATURE PROPERTIES
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// COMPLEX IONS & WHY THEY'RE COLOURED
A transition-metal ion attracts ligands — molecules or ions with a lone pair (water, ammonia, chloride) — which bond to it forming a complex ion, like [Cu(H₂O)₆]²⁺. The ligands split the d-orbitals into two slightly different energy levels. A d-electron can absorb a photon of visible light to jump the gap, so the compound absorbs one colour and we see the rest. Change the ligand (add ammonia to copper sulfate) and you change the size of the gap — and the colour shifts from pale to deep blue before your eyes.
// REFERENCES & FURTHER READING
Cross-check against your own exam board's specification (AQA, Edexcel, OCR, SQA).