CIE A Level Chemistry

Topic Questions

A LevelChemistryCIETopic Questions6. Inorganic Chemistry (A Level Only)6.2 Properties of Transition Elements (A Level Only)

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First teaching 2020

Last exams 2024

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6.2 Properties of Transition Elements (A Level Only)

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1a1 mark

This question is about transition metals. 

Explain what is meant by a transition metal. 

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1b2 marks
i)
State the electronic configuration of Ti2+.
 
[1]
 
ii)
Explain, using the electronic configuration, why zinc is found in the d-block of the periodic table but not classed as a transition metal.
 
[1]

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1c3 marks

Table 1.1 shows sketches of the shapes of some atomic orbitals.

 
Table 1.1 
 
Shape of orbital dxy-orbital s-orbital pz-orbital
Type of orbital    

  
 

Identify the type of orbital, s, p, or d.

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1d2 marks

Transition metals have characteristic properties. One of these properties is that they form coloured ions.

State two other properties that transition metals or their ions exhibit.

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2a2 marks

This question is about transition metal complexes. 

Define the terms ligand and complex.

 

Ligand = ............................................................ 

Complex = ..........................................................

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2b1 mark

Transition metals can form complexes with different ligands.

 

Identify one species from the following list that does not act as a ligand. Explain your answer.

 
CO         H2O         SCN-          H2 

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2c2 marks

A complex contains one Co2+ ion, four ammonia molecules and two chloride ions.

 
i)
State the formula of this complex.
 
[1]
 
ii)
Name the shape of this complex. 
 
[1]

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2d2 marks

The H2O ligands in [Fe(H2O)6]3+ can be exchanged for other ligands. 

 

Predict the shape of the complex ions formed after the following substitutions.

 

i)
All the H2O ligands are exchanged for OH– ligands.
 
[1]
 
ii)
The six H2O ligands are exchanged for four Cl– ligands.
 
[1]

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2e2 marks

Cisplatin can be used to treat some types of cancer.

 

It is a square planar transition metal complex with a central platinum(II) ion, two chloride ligands and two ammonia ligands.

 

Complete the three-dimensional diagram in Fig. 2.1 to show the shape of cisplatin. Label and state the value of one bond angle.

 
 
 
 
Pt
 
 
 
Fig. 2.1 

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3a1 mark

The d-orbitals of a transition metal are involved in the formation of complexes.

In terms of energy, explain what is meant by degenerate orbitals. 

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3b3 marks

Fig. 3.1 shows the shape of the dxy orbital. 

 
dxy-orbital
 
Fig. 3.1
 

The dxz orbital has a similar shape but the lobes are between the x-axis and z-axis and the dyz orbital has a similar shape but the lobes are between the y-axis and z-axis.

 
i)
State the difference between the shape of a dxy orbital and the shape of a dx2–y2 orbital.
 
[1]
 
ii)
Complete the three-dimensional diagram in Fig. 3.2 to show the shape of a dz2 orbital. 
 
xyz-orbital-axes
 
Fig. 3.2 
 
[2] 

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3c1 mark

Suggest what causes d-orbitals in a transition metal ion to change from degenerate to non-degenerate.

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3d2 marks

The splitting of degenerate d-orbitals gives two sets of non-degenerate d-orbitals at different energy levels.

 

Complete Table 3.1 to show the different energy levels of the non-degenerate d-orbitals in octahedral and tetrahedral complexes.

 
Table 3.1 
 
  Higher energy Lower energy
Octahedral    
Tetrahedral    

 

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1a1 mark

Define a transition element.

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1b3 marks
i)
NH3 acts as a monodentate ligand. State what is meant by monodentate ligand.

[2]

ii)
Aqueous silver ions, Ag+ (aq), react with aqueous ammonia, NH3 (aq), to form a linear complex.

Suggest the formula of this complex, including its charge.

[1]

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1c5 marks

There are two isomeric complex ions with the formula [Cr(NH3)4Cl2]+. One is green and the other is violet.

i)
Suggest the type of isomerism shown by these two complex ions.

 [1]

ii)

Explain why these two complex ions are coloured and why they have different colours.

[4]

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1d2 marks

The ligand ethane-1,2-diamine, H2NCH2CH2NH2, is represented by en.
Nickel forms the complex ion [Ni(en)3]2+ in which it is surrounded octahedrally by six nitrogen atoms.

Draw three-dimensional diagrams to show the stereoisomers of [Ni(en)3]2+.

q-6d-9701-y22-sp-4-cie-ial-chem

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1e3 marks

Ethane-1,2-diamine is a useful reagent in organic chemistry.

i)
Explain how the amino groups in ethane-1,2-diamine allow the molecule to act as a Brønsted-Lowry base.

[2]

ii)
Write an equation for the reaction of ethane-1,2-diamine with an excess of hydrochloric acid.

[1]

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1f3 marks
i)
Under certain conditions ethane-1,2-diamine reacts with ethanedioic acid, HOOCCOOH, to form the polymer Z.
Draw the structure of polymer Z, showing two repeat units.

[2]

ii)
Name the type of reaction occurring during this polymerisation.
[1]

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2a6 marks

Copper, vanadium and iron are all transition elements.

i)
Give the full electronic configuration of a Cu atom and a Cu2+ ion.
 
[2]
 
ii)
State four characteristic features of the chemistry of copper and its compounds.
 
[4]

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2b5 marks

The chloride ion is a monodentate ligand. When concentrated hydrochloric acid is added to [Cu(H2O)6]2+ (aq) ions the water ligands are replaced.
 

i)
Define the term monodentate ligand.
 
[1]
 
ii)
Write an equation for the reaction that occurs when concentrated hydrochloric acid is added to [Cu(H2O)6]2+ (aq).
 
[1]
 
iii)
Draw the structure of the complex ion formed and name the shape it takes.
 
[2]
 
iv)
State the change in coordination number. 
 
[1]

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2c3 marks

Vanadium (V) oxide is the catalyst used in the contact process as shown by the reactions:

SO2 + V2O5 → SO3 + V2O4

V2O4 + ½O2 → V2O5

i)
Using the equations, write an overall equation for the reaction.
 
[1]
 
ii)
Using the equations, explain why V2O5 is a catalyst.
 
[1]
 
iii)
Explain why V2O5 is able to act as a catalyst in this reaction.
 
[1]

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2d3 marks

When iron(II) compounds dissolve in water they form [Fe(H2O)6]2+, the hexaaquairon(II) complex.

i)
State the full electronic configuration of an iron(II) ion.
 
[1]
 
ii)
Predict the shape and bond angle of the hexaaquairon(II) complex.
 
[2]

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3a2 marks

A solution is made by dissolving CuSO4•5H2O in an excess of aqueous ammonia. This solution contains the copper complex [Cu(NH3)4]2+.

i)
Write an expression for the Kstab of [Cu(NH3)4]2+.
 
Kstab =
 
[1]
 
ii)
State the colour of the solution of [Cu(NH3)4]2+.
 
[1]

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3b1 mark

The solution of [Cu(NH3)4]2+ is heated gently in a fume cupboard so that NH3 is released. Some NH3 remains in solution and some forms NH3 gas. The colour of the solution changes; a precipitate of Cu(OH)2 forms and is collected.

A sample of Cu(OH)2 is added to concentrated hydrochloric acid. A reaction takes place forming a coloured copper complex, Y.

A sample of Cu(OH)2 is added to dilute sulfuric acid. A reaction takes place forming a coloured copper complex, Z.

[Cu(NH3)4]2+, Y and Z are different colours.

Suggest an equation for the reaction of [Cu(NH3)4]2+ to form Cu(OH)2 as the aqueous solution of [Cu(NH3)4]2+ is heated.

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3c2 marks

Suggest an equation for the reaction of Cu(OH)2 with concentrated hydrochloric acid, forming Y.

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3d2 marks

Complete Table 3.1 with the colour and geometry of complex Y and the colour, geometry and formula of complex Z.

Table 3.1

  Y Z
colour of complex    
geometry of complex    
formula of complex    
 

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3e5 marks

Explain why complexes Y and Z are coloured and why their colours are different.

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4a2 marks

This question is about the geometry and colours of transition metal complexes. 

Explain why transition metals exhibit variable oxidation states compared to the elements in group 1.

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4b3 marks

Transition metal compounds and ions are often coloured. For example, [Cr(H2O)6]3+ is green. 

Explain why [Cr(H2O)6]3+ and other complex ions are coloured.

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4c3 marks

Zinc and cobalt ions react with water to form the complexes [Zn(H2O)4]2+ and [Co(H2O)6]2+.

i)
Explain how water acts as a ligand in forming these complexes.
 
[2]
 
ii)
Predict the shape of [Co(H2O)6]2+.
 
[1]

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4d4 marks

Explain why solutions containing [Co(H2O)6]2+ are coloured but solutions containing [Zn(H2O)4]2+ are not.

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