Stereoisomerism in transition element complexes: past paper questions

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• Question 6May/June 2026, paper 41Structured8 marks

  Transition elements form complexes with species called ligands. The ethanedioate ion, ${\text{C}}_2{\text{O}}_4^{2-}$, is a bidentate ligand. Explain what is meant by bidentate ligand.

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• Question 5Oct/Nov 2025, paper 41Structured14 marks

  Copper shows typical properties of transition elements, including its behaviour as a catalyst. Complete Table 5.1 to show the total number of unpaired electrons in the 3d and 4s orbitals of an isolated gaseous Cu atom and a ${\text{Cu}}^{2+}$ ion.

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• Question 5Oct/Nov 2024, paper 41Structured6 marksHas a diagram

  The shapes of four different complexes, P, Q, R and S, are shown in Table 5.1. The symbol J represents an atom or ion of a transition element. The symbol L is used to represent a monodentate ligand.

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• Question 6Oct/Nov 2023, paper 41Structured6 marks

  Five ligands are listed in Table 6.1.

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• Question 1May/June 2026, paper 42Structured20 marksHas a diagram

  Transition elements have variable oxidation states and form complex ions. State two other typical chemical properties of a transition element.

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• Question 6Oct/Nov 2025, paper 42Structured7 marks

  Nickel forms complexes. Give the formula and charge of the tetrahedral complex formed by $\mathrm{N}\mathrm{i}$ atoms with carbon monoxide molecules.

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• Question 5Oct/Nov 2024, paper 42Structured6 marksHas a diagram

  ${\text{Ni}}^{2+}$ ions form a number of different complex ions, including $[\text{Ni}({\text{H}}_2\text{O}{)}_6{]}^{2+}$, $[\text{Ni}({\text{NH}}_3{)}_6{]}^{2+}$ and $[\text{Ni}(\text{en}{)}_3{]}^{2+}$. The abbreviation en represents 1,2-diaminoethane.

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• Question 6Oct/Nov 2023, paper 42Structured10 marksHas a diagram

  Phosphine, $:\mathrm{P}{\mathrm{H}}_3$, and carbon monoxide, $:\mathrm{C}\mathrm{O}$, are monodentate ligands found in some transition element complexes. Define monodentate ligand.

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• Question 3May/June 2024, paper 41Structured13 marksHas a diagram

  When a sample of hydrated lithium ethanedioate, $\mathrm{L}{\mathrm{i}}_2{\mathrm{C}}_2{\mathrm{O}}_4\cdot {\mathrm{H}}_2\mathrm{O}$, is gently heated, two gaseous products are formed and a white solid residue remains. The residue is added to $\mathrm{H}\mathrm{N}{\mathrm{O}}_3(\mathrm{a}\mathrm{q})$. A gas is produced that turns limewater milky.

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• Question 2May/June 2023, paper 41Structured11 marksHas a diagram

  Some transition element complexes can show stereoisomerism.

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• Question 4May/June 2024, paper 42Structured14 marksHas a diagram

  Explain why transition elements have variable oxidation states.

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• Question 2May/June 2023, paper 42Structured12 marksHas a diagram

  State two typical chemical properties of a transition element.

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