What a learner can do afterwards
- Defines a transition element by its d sub-shell and explains why scandium and zinc do not qualify
- Gives the common oxidation states of a named transition metal with a compound of each
- Explains colour as a d sub-shell split by ligands, with part of the visible spectrum absorbed
- Names a heterogeneous and a homogeneous catalyst and explains the part the oxidation states play
1 · Read
A transition metal has a partly filled d sub-shell, or easily forms an ion with one. Scandium only reaches Sc3+ with an empty d sub-shell, and zinc sits at Zn2+ with a full one, so neither qualifies even though both sit in the block.
Iron shows the flexible side: Fe2+ in FeCl2 and Fe3+ in FeCl3. Reaching for different electron counts is exactly what the roomy d sub-shell allows, and you can name a compound for each state.
Ligands split the d sub-shell into new levels, and electrons jumping the gap swallow part of the visible light. Copper compounds look coloured, while zinc compounds stay white, since a full sub-shell has no gap to jump.
Many of these metals catalyse because their oxidation states flip back and forth mid-route. Nitric oxide gas catalyses ozone loss the same way gases meet, with nitrogen going +2 to +4 and back, while a car converter works with gases streaming past a catalyst that stays put. A catalyst in a different phase from the reactants is heterogeneous, like the converter surface with exhaust gases. One mixed in the same phase is homogeneous, like NO gas with ozone.
Part-filled d shells bring many states, split levels bring colour, and flipping states brings catalysis.
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8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.