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Edexcel International A Level Chemistry

Topic 17
Transition Metals
and their
Chemistry

Topic 17 follows Redox Equilibria in Unit 5. It covers the electronic configurations of the d-block atoms and ions from scandium to zinc and why transition metals show variable oxidation numbers; ligands, dative (coordinate) covalent bonding, coordination number and the octahedral, tetrahedral and square planar shapes of complex ions, with cis-platin and haemoglobin; the origin of colour; the redox chemistry of vanadium and chromium in terms of E⦵ values; reactions of eight aqueous metal ions with sodium hydroxide and ammonia; ligand exchange and the stability of complexes; and heterogeneous catalysis, homogeneous catalysis and autocatalysis.

Exam Unit
Unit 5
WCH15/01 – IAL
Specification Points
17.1 – 17.33
33 points covered
Sub-topics
8 lessons
Revision notes available
Exam Board
Edexcel IAL
Pearson International

Revision Notes

8 revision notes, in the order the specification teaches them.

Five orbital boxes filling with electrons
1

Electron Configurations and Properties of Transition metals

Transition metals: electron configurations of d-block atoms and ions, the definition of a transition metal and variable oxidation numbers.

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An octahedral complex with coloured solutions
2

Ligands, Complex Ions and Their Shapes

Ligands and complex ions: dative (coordinate) covalent bonds, coordination number, bidentate and polydentate ligands and the shapes of complexes.

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White light passing through a blue solution
3

Colour of Transition metal Ions

The colour of transition metal ions: d-orbital splitting, absorption of visible light and the effect of oxidation number, ligand and coordination number.

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A pale blue solution turning deep blue on adding a ligand
4

Ligand exchange and the Stability of Complexes

Ligand exchange in copper(II) and cobalt(II) complexes, the chelate effect and entropy.

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Four tubes of yellow, blue, green and violet solution
5

Redox Chemistry of Transition metals

Transition metal redox reactions: vanadium oxidation states, chromium and dichromate(VI) and colour changes.

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Test tubes of coloured precipitates
6

Reactions of Metal Ions with Sodium Hydroxide and Ammonia

Reactions of aqueous metal ions with sodium hydroxide and ammonia: precipitate colours, ionic equations and amphoteric hydroxides.

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Gas molecules adsorbing on a solid metal surface
7

Heterogeneous Catalysis

Transition metals as heterogeneous catalysts: surface adsorption, V₂O₅ in the Contact process and catalytic converters.

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An S-shaped curve beside a fading purple flask
8

Homogeneous Catalysis and Autocatalysis

Homogeneous catalysis: Fe²⁺ with I⁻ and S₂O₈²⁻, and autocatalysis by Mn²⁺ in the MnO₄⁻ and C₂O₄²⁻ reaction.

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Summary Map

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Summary maps

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Illustration of a summary map: compounds joined by reaction arrows
Summary map · PDF

Transition Metals Map

Edexcel International A Level Chemistry · Unit 5 · Topic 17A Transition Metals and Complexes

The whole section on one A4 page: what makes a transition metal, configurations, oxidation numbers, ligands and complexes, multidentate ligands, and cisplatin and haemoglobin.

Download the map6 key ideas + a data table · A4 portrait · print ready
Illustration of a summary map: compounds joined by reaction arrows
Summary map · PDF

Transition Metal Reactions Map

Edexcel International A Level Chemistry · Unit 5 · Topic 17B Colour, Redox and Reactions of Ions

The whole section on one A4 page: why ions are coloured, changing the colour, vanadium, chromium, hydroxide precipitates, excess ammonia and Core Practical 14.

Download the map6 key ideas + a data table · A4 portrait · print ready
Illustration of a summary map: compounds joined by reaction arrows
Summary map · PDF

Exchange and Catalysis Map

Edexcel International A Level Chemistry · Unit 5 · Topic 17C Ligand Exchange and Catalysis

The whole section on one A4 page: ligand exchange, the chelate effect, heterogeneous and homogeneous catalysts, V₂O₅, catalytic converters and autocatalysis.

Download the map6 key ideas + a data table · A4 portrait · print ready

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17.1

  1. a

    know that transition metals are d-block elements

    Revise
  2. b

    know that transition metals form one or more stable ions with incompletely-filled d-orbitals

    Revise

17.2

  1. a

    be able to deduce electronic configurations of atoms of d-block Period 4 elements Sc-Zn

    Revise
  2. b

    be able to deduce electronic configurations of ions of d-block Period 4 elements Sc-Zn

    Revise

17.3

  1. 17.3

    understand why transition metals show variable oxidation number

    Revise

17.4

  1. 17.4

    know what is meant by the term ‘ligand’

    Revise

17.5

  1. 17.5

    understand that dative (coordinate) covalent bonding is involved in the formation of complex ions

    Revise

17.6

  1. 17.6

    know that a complex ion is a central metal ion surrounded by ligands

    Revise

17.7

  1. 17.7

    know that aqueous solutions of transition metal ions are usually coloured

    Revise

17.8

  1. a

    understand that colour of aqueous transition metal ions is a consequence of splitting of d-orbital energy levels by ligands

    Revise
  2. b

    understand that colour of other complex ions is a consequence of splitting of d-orbital energy levels by ligands

    Revise

17.9

  1. a

    understand why there is a lack of colour in some aqueous ions

    Revise
  2. b

    understand why there is a lack of colour in some complex ions

    Revise

17.10

  1. 17.10

    understand the meaning of the term ‘coordination number’

    Revise

17.11

  1. i

    understand that colour changes in transition metal ions may arise as a result of changes in: oxidation number of the ion

    Revise
  2. ii

    understand that colour changes in transition metal ions may arise as a result of changes in: ligand

    Revise
  3. iii

    understand that colour changes in transition metal ions may arise as a result of changes in: coordination number of the complex

    Revise

17.12

  1. a

    understand that H2O acts as a monodentate ligand

    Revise
  2. b

    understand that OH- acts as a monodentate ligand

    Revise
  3. c

    understand that NH3 acts as a monodentate ligand

    Revise

17.13

  1. a

    understand why complexes with six-fold coordination have octahedral shape

    Revise
  2. b

    know that octahedral complexes can be formed by metal ions with H2O ligands

    Revise
  3. c

    know that octahedral complexes can be formed by metal ions with OH- ligands

    Revise
  4. d

    know that octahedral complexes can be formed by metal ions with NH3 ligands

    Revise

17.14

  1. 17.14

    know that transition metal ions may form tetrahedral complexes with relatively large ions such as Cl-

    Revise

17.15

  1. a

    know that square planar complexes are formed by transition metal ions

    Revise
  2. b

    know that cis-platin is a square planar complex used in cancer treatment

    Revise
  3. c

    know that cis-platin is supplied as a single isomer and not mixed with the trans form

    Revise

17.16

  1. a

    understand the term 'bidentate' in relation to ligands

    Revise
  2. b

    understand the term 'hexadentate' in relation to ligands

    Revise
  3. c

    be able to identify NH2CH2CH2NH2 as a bidentate ligand

    Revise
  4. d

    be able to identify EDTA4- as a hexadentate ligand

    Revise

17.17

  1. a

    know that haemoglobin is an iron(II) complex containing a polydentate ligand

    Revise
  2. b

    know that ligand exchange occurs when oxygen bound to haemoglobin is replaced by carbon monoxide

    Revise
  3. c

    know that the structure of the haem group will not be assessed

    Revise

17.18

  1. a

    know the colour of vanadium in oxidation state +5

    Revise
  2. b

    know the colour of vanadium in oxidation state +4

    Revise
  3. c

    know the colour of vanadium in oxidation state +3

    Revise
  4. d

    know the colour of vanadium in oxidation state +2

    Revise

17.19

  1. a

    understand redox reactions for interconversion of vanadium oxidation states +5 and +4 in terms of relevant Eo values

    Revise
  2. b

    understand redox reactions for interconversion of vanadium oxidation states +4 and +3 in terms of relevant Eo values

    Revise
  3. c

    understand redox reactions for interconversion of vanadium oxidation states +3 and +2 in terms of relevant Eo values

    Revise

17.20

  1. i

    understand, in terms of the relevant E values, that the dichromate(VI) ion, Cr2O72- can be reduced to Cr3+ and Cr2+ ions using zinc in acidic conditions

    Revise
  2. ii

    understand, in terms of the relevant E values, that the dichromate(VI) ion, Cr2O72- can be produced by the oxidation of Cr3+ ions using hydrogen peroxide in alkaline conditions (followed by acidification)

    Revise

17.21

  1. a

    know that dichromate(VI) ions can be converted into chromate(VI) ions

    Revise
  2. b

    know the equilibrium Cr2O72- + H2O ⇌ 2CrO42- + 2H+

    Revise

17.22

  1. a

    be able to record observations and write suitable equations for reactions of Cr3+(aq) with aqueous sodium hydroxide

    Revise
  2. aa

    be able to record observations and write suitable equations for reactions of Cu2+(aq) with aqueous ammonia

    Revise
  3. ab

    be able to record observations and write suitable equations for reactions of Cu2+(aq) with aqueous ammonia in excess

    Revise
  4. ac

    be able to record observations and write suitable equations for reactions of Zn2+(aq) with aqueous sodium hydroxide

    Revise
  5. ad

    be able to record observations and write suitable equations for reactions of Zn2+(aq) with aqueous sodium hydroxide in excess

    Revise
  6. ae

    be able to record observations and write suitable equations for reactions of Zn2+(aq) with aqueous ammonia

    Revise
  7. af

    be able to record observations and write suitable equations for reactions of Zn2+(aq) with aqueous ammonia in excess

    Revise
  8. b

    be able to record observations and write suitable equations for reactions of Cr3+(aq) with aqueous sodium hydroxide in excess

    Revise
  9. c

    be able to record observations and write suitable equations for reactions of Cr3+(aq) with aqueous ammonia

    Revise
  10. d

    be able to record observations and write suitable equations for reactions of Cr3+(aq) with aqueous ammonia in excess

    Revise
  11. e

    be able to record observations and write suitable equations for reactions of Mn2+(aq) with aqueous sodium hydroxide

    Revise
  12. f

    be able to record observations and write suitable equations for reactions of Mn2+(aq) with aqueous sodium hydroxide in excess

    Revise
  13. g

    be able to record observations and write suitable equations for reactions of Mn2+(aq) with aqueous ammonia

    Revise
  14. h

    be able to record observations and write suitable equations for reactions of Mn2+(aq) with aqueous ammonia in excess

    Revise
  15. i

    be able to record observations and write suitable equations for reactions of Fe2+(aq) with aqueous sodium hydroxide

    Revise
  16. j

    be able to record observations and write suitable equations for reactions of Fe2+(aq) with aqueous sodium hydroxide in excess

    Revise
  17. k

    be able to record observations and write suitable equations for reactions of Fe2+(aq) with aqueous ammonia

    Revise
  18. l

    be able to record observations and write suitable equations for reactions of Fe2+(aq) with aqueous ammonia in excess

    Revise
  19. m

    be able to record observations and write suitable equations for reactions of Fe3+(aq) with aqueous sodium hydroxide

    Revise
  20. n

    be able to record observations and write suitable equations for reactions of Fe3+(aq) with aqueous sodium hydroxide in excess

    Revise
  21. o

    be able to record observations and write suitable equations for reactions of Fe3+(aq) with aqueous ammonia

    Revise
  22. p

    be able to record observations and write suitable equations for reactions of Fe3+(aq) with aqueous ammonia in excess

    Revise
  23. q

    be able to record observations and write suitable equations for reactions of Co2+(aq) with aqueous sodium hydroxide

    Revise
  24. r

    be able to record observations and write suitable equations for reactions of Co2+(aq) with aqueous sodium hydroxide in excess

    Revise
  25. s

    be able to record observations and write suitable equations for reactions of Co2+(aq) with aqueous ammonia

    Revise
  26. t

    be able to record observations and write suitable equations for reactions of Co2+(aq) with aqueous ammonia in excess

    Revise
  27. u

    be able to record observations and write suitable equations for reactions of Ni2+(aq) with aqueous sodium hydroxide

    Revise
  28. v

    be able to record observations and write suitable equations for reactions of Ni2+(aq) with aqueous sodium hydroxide in excess

    Revise
  29. w

    be able to record observations and write suitable equations for reactions of Ni2+(aq) with aqueous ammonia

    Revise
  30. x

    be able to record observations and write suitable equations for reactions of Ni2+(aq) with aqueous ammonia in excess

    Revise
  31. y

    be able to record observations and write suitable equations for reactions of Cu2+(aq) with aqueous sodium hydroxide

    Revise
  32. z

    be able to record observations and write suitable equations for reactions of Cu2+(aq) with aqueous sodium hydroxide in excess

    Revise

17.23

  1. a

    be able to write ionic equations to show amphoteric behaviour in reactions in 17.22

    Revise
  2. b

    be able to write ionic equations to show deprotonation in reactions in 17.22

    Revise
  3. c

    be able to write ionic equations to show ligand exchange in reactions in 17.22

    Revise

17.24

  1. i

    understand that ligand exchange, and an accompanying colour change, occurs in the formation of: [Cu(NH3)4(H2O)2]2+ from [Cu(H2O)6]2+ via Cu(OH)2(H2O)4

    Revise
  2. ii

    understand that ligand exchange, and an accompanying colour change, occurs in the formation of: [CuCl4]2- from [Cu(H2O)6]2+

    Revise
  3. iii

    understand that ligand exchange, and an accompanying colour change, occurs in the formation of: [CoCl4]2- from [Co(H2O)6]2+

    Revise

17.25

  1. a

    understand that substitution of a monodentate ligand by a bidentate ligand leads to a more stable complex ion due to positive increase in ΔSsystem

    Revise
  2. b

    understand that substitution of a monodentate ligand by a hexadentate ligand leads to a more stable complex ion due to positive increase in ΔSsystem

    Revise

17.26

  1. a

    know that transition metals can act as heterogeneous catalysts

    Revise
  2. b

    know that transition metals can act as homogeneous catalysts

    Revise
  3. c

    know that transition metal compounds can act as heterogeneous catalysts

    Revise
  4. d

    know that transition metal compounds can act as homogeneous catalysts

    Revise

17.27

  1. a

    know that a heterogeneous catalyst is in a different phase from the reactants

    Revise
  2. b

    know that reaction occurs at the surface of a heterogeneous catalyst

    Revise

17.28

  1. 17.28

    understand, in terms of oxidation number, how V2O5 acts as a catalyst in the contact process

    Revise

17.29

  1. i a

    understand how catalytic converters decrease carbon monoxide emissions by adsorption of CO onto the catalyst surface

    Revise
  2. i b

    understand how catalytic converters decrease nitrogen monoxide emissions by adsorption of NO onto the catalyst surface

    Revise
  3. i c

    understand that adsorption weakens bonds and enables chemical reaction on the catalyst surface

    Revise
  4. ii a

    understand how catalytic converters decrease emissions by desorption of CO2 product molecules

    Revise
  5. ii b

    understand how catalytic converters decrease emissions by desorption of N2 product molecules

    Revise

17.30

  1. a

    know that a homogeneous catalyst is in the same phase as the reactants

    Revise
  2. b

    appreciate that a homogeneously catalysed reaction proceeds via an intermediate species

    Revise

17.31

  1. 17.31

    understand the role of Fe2+ ions in catalysing the reaction between I- and S2O8 2- ions

    Revise

17.32

  1. 17.32

    know the role of Mn2+ ions in autocatalysing the reaction between MnO4 - and C2O4 2- ions

    Revise

17.33

  1. 17.33

    CORE PRACTICAL 14 The preparation of a transition metal complex.