DP IB Chemistry: HL

Topic Questions

IBChemistry: HLDPTopic Questions13. The Periodic Table- Transition Metals (HL only)13.1 Transition Metals

Syllabus Edition

First teaching 2014

Last exams 2024

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13.1 Transition Metals

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1a2 marks

Transition metals can form complex ions where ligands are coordinately bonded to the central metal ion.

i)    Define the term ligand.

[1]

ii)    State what is meant by the term bidentate ligand

[1]

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1b2 marks

Transition metals are located in the d-block of the periodic table.

i)
State the electron configuration of V2+.

[1]

ii)
Explain why scandium is not considered a transition metal.

[1]

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1c1 mark

State the oxidation state of Fe in [Fe(CN)6]4−.

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1d3 marks

Iron and zinc are in the d-block of the Periodic Table. Iron(II) ions, [Fe(H2O)6]2+, form a pale green solution but zinc ions,   [Zn(H2O)6]2+, form a colourless solution.

i)
Write the electron configuration of Zn2+.
[1]
ii)
Explain why zinc ions are colourless.
[2]

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2a1 mark

A complex ion contains one Fe3+ ion, four ammonia molecules and two chloride ions.

State the formula of this complex ion.

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2b2 marks

State two characteristic properties of transition elements.

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2c1 mark

Transition metals can be used as successful catalysts in a range of reactions.

State what is meant by the term homogeneous catalyst.

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2d2 marks

Transition metals can form complexes with different ligands.

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


CO         H2O         SCN-          H2

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3a1 mark

Using section 16 of the data booklet, state the formula of a bidentate ligand.

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3b3 marks
State three factors that affect the value of the splitting energy, ΔE, in the d-orbitals.

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3c5 marks

Outline why transition metals form coloured compounds.

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3d2 marks

Using section 15 of the data booklet, explain why adding ammonia to aqueous copper(II) ions results in a darker blue complex.

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4a1 mark

Deduce the oxidation state of vanadium in the compound NH4VO3.

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4b1 mark

Transition elements can be used to catalyse certain reactions.

Define the term heterogeneous in relation to catalysts.

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4c1 mark

Outline the difference between diamagnetic and paramagnetic elements in terms of electron arrangement.

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4d1 mark

Describe the splitting of the d orbitals in an octahedral crystal field.

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1a4 marks

When chromium(III) sulfate dissolves in water, a green solution containing the [Cr(H2O)6]3+ ion forms.

i)
State the bond angles found in this complex ion.
[1]
ii)
Explain why the chromium(III) complex ion is coloured.
[3]

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1b2 marks

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

SO2 (g) + V2O5 (s) → SO3 (g) + V2O4 (s)

V2O4 (s) + ½O2 (g) → V2O5 (s)

i)     Explain, using the equations, why V2O5 is a catalyst.

[1]

ii)     Explain why V2O5 can act as a catalyst in this reaction.

[1]

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1c1 mark

Excess ammonia is added to a solution of Cu2+ ions resulting in the substitution of 4 ligands.

Using section 15 of the data booklet, explain why this reaction results in a shift in the wavelength of light absorbed by the Cu2+ complex.

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2a1 mark

Iron is a transition element that forms several ions with iron in different oxidation states.

Deduce the condensed electron configuration of the iron cation that can form the complex ion [Fe(CN)6]4−.

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2b2 marks

Co(III) has the same electron configuration as the iron cation in part(a). 

Explain why, despite this, solutions of the two ions are different colours.

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2c1 mark

Rhenium forms salts containing the perrhenate(VII) ion, ReO4−.

Suggest why the existence of salts containing an ion with this formula could be predicted. Refer to section 6 of the data booklet.

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2d2 marks

Rhenium is used with platinum to speed up reactions used in the production of gasoline.

Predict two other chemical properties you would expect rhenium to have, given its position in the periodic table.

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3a2 marks

Chromium (III) picolinate, shown below, is often used in tablets as a nutritional supplement for chromium.

chromium-piccolate

i)    Draw the structure of the ligand in chromium(III) picolinate.

[1]

ii)          State the coordination number of chromium in chromium(III) picolinate.

[1]

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3b3 marks

A complex of cobalt has the following composition by mass:

Co, 21.98%; N, 31.35%; H, 6.81%; Cl, 39.86%

i)
Calculate the empirical formula of this complex.

ii)
The formula of this cobalt complex can be expressed in the form [Co(L)m]x+(Cl−)n.
Suggest the chemical formula of [Co(L)m]x+.

[3]

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3c2 marks

Ni(ClO4)2 reacts with water to form the complex ion [Ni(H2O)6][ClO4]2.

Explain this reaction in terms of an acid-base theory.

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3d2 marks

Nickel(II) forms a complex ion with water, [Ni(H2O)6]2+

i)
Outline how the bond is formed between Ni2+ and H2O during the formation of the complex.

[1]

ii}        State the geometry of the complex formed.

[1]

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4a2 marks

1,2-diaminoethane is a bidentate ligand which can form a complex with [Co(NH3)4(H2O)2]2+. In this reaction, only the ammonia molecules are replaced.                                              

i)    Write an equation for this reaction.

[1]

ii)          State the molecular geometry of the complex formed.

[1]

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4b3 marks

Consider the complex [Ni(NH3)6]Cl2

i)
Deduce the condensed electron configuration of the Ni.
[1]
ii)
Explain whether the complex is paramagnetic or diamagnetic.
[2]

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4c2 marks

Explain why Ti forms variable oxidation states, but Ca only occurs in the +2 oxidation state. 

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4d2 marks

Explain the magnetic nature of the complex [Cr(H2O)6]Cl3.

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1a2 marks
a)
Explain why transition metals exhibit variable oxidation states compared to the elements in group 1.

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1b3 marks
b)

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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1c3 marks
c)

Water acts as a ligand when it reacts with zinc and cobalt ions, forming the complexes [Zn(H2O)4]2+ and [Co(H2O)6]2+ 

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

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1d4 marks
d)
Explain why solutions containing [Co(H2O)6]2+ are coloured but solutions containing [Zn(H2O)4]2+ are not.

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2a3 marks
a)
Complete Table 1 below to show the oxidation state of the transition element.

Table 1

Ion

[Cu(Cl4)]2-

[Fe(H2O)6]3+

Cr2O72-

Oxidation state

 

 

 

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2b3 marks
b)
Explain why chromium is the most paramagnetic element in the first transition series and why zinc is diamagnetic.

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2c3 marks
c)
EUK-134 is a complex ion of manganese(III) used in skin care products to protect against UV damage as it has antioxidant properties.
q2c_13-1_medium_ib_hl_sq
i)
State the electron configuration of the manganese(III) ion in complex shown above

ii)
State the name given to species that bond to a central metal ion, and identify the type of bond present.

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2d2 marks
d)

Transition metals have certain characteristic properties.

State two properties that are involved in EUK-134 rapidly decreasing the concentration of oxidising agents. 

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3a5 marks
a)
A characteristic property of transition elements, like chromium, is that they form coloured compounds. Using Section 17 of the Data Booklet, explain why Ni2+(aq) is green but Sc3+(aq) is colourless.

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3b3 marks
b)

The colour intensity of solutions of complex ions is one method of determining the concentration of transition metal ions. Excess aqueous ammonia is sometimes added before measuring the absorption of copper(II) ions. 

Describe why the addition of excess ammonia to aqueous copper(II) ions causes the shade of the blue colour to change.

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3c2 marks
c)

Increasing the concentration of chloride ions in an aqueous solution of vanadium(III) chloride causes the vanadium complex to change from [V(H2O)6]3+ to [VCl (H2O)5]2+ to [VCl2(H2O)4]+ 

Outline what would happen to the wavelength at which the vanadium complex ions would absorb light as the concentration of chloride ions is increased, using Section 15 of the Data Booklet.

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3d2 marks
d)
Ferrocyanide salts,  [Fe(CN)6]4−, are used in the production of Prussian blue, which was the first modern synthetic pigment.

i)
Deduce the oxidation number of iron in [Fe(CN)6]4−

ii)
Draw the abbreviated orbital diagram for the iron ion in [Fe(CN)6]4– using the arrow-in-box notation to represent electrons.

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4a1 mark
a)

The energy level diagram showing the electrons in the five 3d orbitals of a chromium atom is shown in the figure below. 

Draw the completed diagram showing the d orbitals in [Cr(H2O)6]3+ after splitting.

q4a_13-1_medium_ib_hl

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4b2 marks
a)
State and explain what happens to the splitting of the d orbitals if the ligand is changed from H2O to NH3.

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4c2 marks
c)
Explain, in terms of acid-base theories, what type of a reaction is the formation of [Fe(H2O)6]2+ from Fe2+ and water

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4d4 marks
d)

The complex ion [Ni(NH3)6]2+ is blue and [Ni(H2O)6]2+  is green 

Explain why the  [Ni(H2O)6]2+ complex ion is coloured and outline why changing the identity of the ligand changes the colour of the ion.

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5a4 marks
a)

Dilute copper(II) chloride solution is light blue, while copper(I) chloride is colourless. 

Describe how the blue colour is produced in the copper(II) chloride. Refer to Section 17 of the Data Booklet.

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5b2 marks
b)
Explain why the copper(I) chloride is colourless.

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5c2 marks
c)

When excess ammonia is added to copper(II) chloride solution, the dark blue complex ion, [Cu(NH3)4(H2O)2]2+, forms. 

State the molecular geometry of this complex ion, and the bond angles within it.

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5d3 marks
d)

Outline the relationship between the Brønsted–Lowry and Lewis definitions of a base, referring to the ligands in the complex ion [CuCl4]2−.

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