Transition Metals

What Transition Metals covers

Covers what makes an element a transition metal, complex ions and their shapes, why the complexes are coloured, ligand exchange, the chemistry of the individual metals, and their catalytic behaviour.

The 9 subtopics

Each one has its own page.

• Electron configuration and what makes a transition metalRecall questions on the d-block configurations, on the exceptions at chromium and copper, on which elements are excluded, and on variable oxidation states.Open →
• Complex ions, ligands and the colour of transition metal ionsLigands, dative bonds and complex ions, why transition metal ions are coloured through d-orbital splitting and d-d transitions, why d⁰ and d¹⁰ ions are colourless, and how a change of oxidation number, ligand or coordination number changes the colour.Open →
• Coordination number, monodentate ligands and the shapes of complexesCoordination number, water, hydroxide ions and ammonia as monodentate ligands, octahedral complexes with 90° bond angles, tetrahedral complexes with chloride ions at 109.5°, and square planar complexes such as cisplatin.Open →
• Bidentate and multidentate ligands, and ligand exchangeWhy cisplatin is supplied as a single isomer, bidentate ligands such as ethane-1,2-diamine, the multidentate ligand EDTA⁴⁻, haemoglobin as an iron(II) complex, and the ligand exchange by which carbon monoxide displaces oxygen.Open →
• Vanadium and chromium chemistryThe colours of vanadium in its +5, +4, +3 and +2 oxidation states, using E° values to explain reduction by zinc in acid, reducing dichromate(VI) to Cr³⁺ and Cr²⁺ with zinc, oxidising Cr³⁺ with alkaline hydrogen peroxide, and the chromate(VI) and dichromate(VI) equilibrium.Open →
• Reactions with sodium hydroxide and ammoniaThe hydroxide precipitates Cr³⁺, Fe²⁺, Fe³⁺ and Co²⁺ give with sodium hydroxide and ammonia and which dissolve in excess, the oxidation of Fe(OH)₂ in air, and Core Practical 12 preparing tetraamminecopper(II) sulfate, with its purpose, equation, method, safety and yield.Open →
• Cobalt and copper complexesCobalt(II) and copper(II) ions with sodium hydroxide and ammonia and which precipitates dissolve in excess, ligand exchange to deep blue [Cu(NH₃)₄(H₂O)₂]²⁺ in excess ammonia and its equation, and the colours of [Cu(H₂O)₆]²⁺ and the copper hydroxide precipitate.Open →
• Ligand exchange, amphoteric behaviour and the chelate effectDefining ligand exchange and amphoteric behaviour, Cr(OH)₃ dissolving in excess hydroxide, the colour of the copper ammine complex, ligand exchange with concentrated hydrochloric acid to give [CuCl₄]²⁻ and [CoCl₄]²⁻, why the coordination number falls from six to four, and the chelate effect explained by the entropy change.Open →
• Transition metals as catalystsHeterogeneous and homogeneous catalysis by transition metals, vanadium(V) oxide in the contact process, adsorption, reaction and desorption in a catalytic converter, Fe²⁺ catalysing the reaction between I⁻ and S₂O₈²⁻, and Mn²⁺ as an autocatalyst in the reaction of MnO₄⁻ with C₂O₄²⁻.Open →

What you need to know

Answer each one before you reveal it.

Take Transition Metals further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Ligand vs Complex ion

  Ligand: electron-pair donor forming a coordinate bond. Complex ion: charged metal centre surrounded by coordinate-bonded species.

• Monodentate ligand vs Bidentate ligand

  Monodentate ligand: donor forming one coordinate bond. Bidentate ligand: donor forming two coordinate bonds.

• Ligand substitution vs Redox reaction

  Ligand substitution: replacement of a donor around a metal centre. Redox reaction: electron transfer changing oxidation states.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is the general pattern for the electronic configuration of d-block elements?

   Model answer

   [Ar] 3dⁿ 4s² or [Ar] 3dⁿ 4s¹, where electrons fill the 4s orbital before the 3d orbitals.

2. 2

   Why do electrons fill the 4s orbital before the 3d orbitals in d-block elements?

   Model answer

   The 4s orbital is at a lower energy level than the 3d orbitals, so it fills first according to the aufbau principle.

3. 3

   State the electronic configuration of chromium.

   Model answer

   [Ar] 3d⁵ 4s¹

4. 4

   Why does chromium have an anomalous electronic configuration?

   Model answer

   A half-filled d-subshell provides extra stability, so one electron from the 4s orbital moves to the 3d subshell to achieve 3d⁵ 4s¹.

5. 5

   State the electronic configuration of copper.

   Model answer

   [Ar] 3d¹⁰ 4s¹

6. 6

   Why does copper have an anomalous electronic configuration?

   Model answer

   A fully-filled d-subshell provides extra stability, so one electron from the 4s orbital moves to the 3d subshell to achieve 3d¹⁰ 4s¹.

What is inside Levo

Six ways to work the same material.

Transition Metals revision questions

What does Transition Metals cover in Edexcel A-Level Chemistry?

9 subtopics: electron configuration and what makes a transition metal, complex ions, ligands and the colour of transition metal ions, coordination number, monodentate ligands and the shapes of complexes, bidentate and multidentate ligands, and ligand exchange, vanadium and chromium chemistry, reactions with sodium hydroxide and ammonia, cobalt and copper complexes, ligand exchange, amphoteric behaviour and the chelate effect and transition metals as catalysts. Each one has its own page with questions and model answers.

How is Transition Metals organised?

By the Edexcel 9CH0 specification, subtopic by subtopic, so it matches the order you are taught it in.