Topic 17: Transition Metals and their Chemistry

Know that transition metals are d-block elements that form one or more stable ions with incompletely-filled d-orbitals.

Use —transition metals are d-block elements that form one or more stable ions with incompletely-filled d-orbitals to connect the rule to the data and decision in the question.

This matters because —transition metals are d-block elements that form one or more stable ions with incompletely-filled d-orbitals determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —transition metals are d-block elements that form one or more stable ions with incompletely-filled d-orbitals to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Transition metals are d-block elements that form one or more stable ions with incompletely-filled d-orbitals is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to deduce the electronic configurations of atoms and ions of the d-block elements of Period 4 (Sc-Zn) given their atomic number and charge (if any).

Use —deduce the electronic configurations of atoms and ions of the d-block elements of period 4 (sc-zn) given their atomic number to connect the rule to the data and decision in the question.

This matters because —deduce the electronic configurations of atoms and ions of the d-block elements of period 4 (sc-zn) given their atomic number determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —deduce the electronic configurations of atoms and ions of the d-block elements of period 4 (sc-zn) given their atomic number to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Deduce the electronic configurations of atoms and ions of the d-block elements of Period 4 (Sc-Zn) given their atomic number is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand why transition metals show variable oxidation number.

Use —why transition metals show variable oxidation number to connect the rule to the data and decision in the question.

This matters because —why transition metals show variable oxidation number determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —why transition metals show variable oxidation number to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Why transition metals show variable oxidation number is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know what is meant by the term ‘ligand’.

Use —what is meant by the term ‘ligand’ to connect the rule to the data and decision in the question.

This matters because —what is meant by the term ‘ligand’ determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —what is meant by the term ‘ligand’ to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —What is meant by the term ‘ligand’ is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

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

Use —dative (coordinate) covalent bonding is involved in the formation of complex ions to connect the rule to the data and decision in the question.

This matters because —dative (coordinate) covalent bonding is involved in the formation of complex ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —dative (coordinate) covalent bonding is involved in the formation of complex ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Dative (coordinate) covalent bonding is involved in the formation of complex ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that a complex ion is a central metal ion surrounded by ligands.

Use —a complex ion is a central metal ion surrounded by ligands to connect the rule to the data and decision in the question.

This matters because —a complex ion is a central metal ion surrounded by ligands determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —a complex ion is a central metal ion surrounded by ligands to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —A complex ion is a central metal ion surrounded by ligands is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that aqueous solutions of transition metal ions are usually coloured.

Use —aqueous solutions of transition metal ions are usually coloured to connect the rule to the data and decision in the question.

This matters because —aqueous solutions of transition metal ions are usually coloured determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —aqueous solutions of transition metal ions are usually coloured to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Aqueous solutions of transition metal ions are usually coloured is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand that the colour of aqueous ions, and other complex ions, is a consequence of the splitting of the energy levels of the d-orbitals by ligands.

Use —the colour of aqueous ions, and other complex ions, is a consequence of the splitting of the energy levels of the d-orbitals to connect the rule to the data and decision in the question.

This matters because —the colour of aqueous ions, and other complex ions, is a consequence of the splitting of the energy levels of the d-orbitals determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the colour of aqueous ions, and other complex ions, is a consequence of the splitting of the energy levels of the d-orbitals to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The colour of aqueous ions, and other complex ions, is a consequence of the splitting of the energy levels of the d-orbitals is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand why there is a lack of colour in some aqueous ions and other complex ions.

Use —why there is a lack of colour in some aqueous ions and other complex ions to connect the rule to the data and decision in the question.

This matters because —why there is a lack of colour in some aqueous ions and other complex ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —why there is a lack of colour in some aqueous ions and other complex ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Why there is a lack of colour in some aqueous ions and other complex ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the meaning of the term ‘coordination number’.

Use —the meaning of the term ‘coordination number’ to connect the rule to the data and decision in the question.

This matters because —the meaning of the term ‘coordination number’ determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the meaning of the term ‘coordination number’ to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The meaning of the term ‘coordination number’ is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand that colour changes in transition metal ions may arise as a result of changes in: i oxidation number of the ion ii ligand iii coordination number of the complex.

Use —colour changes in transition metal ions may arise as a result of changes in: i oxidation number of the ion ii ligand iii to connect the rule to the data and decision in the question.

This matters because —colour changes in transition metal ions may arise as a result of changes in: i oxidation number of the ion ii ligand iii determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —colour changes in transition metal ions may arise as a result of changes in: i oxidation number of the ion ii ligand iii to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Colour changes in transition metal ions may arise as a result of changes in: i oxidation number of the ion ii ligand iii is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand that H2O, OH- and NH3 act as monodentate ligands.

Use —h2o, oh- and nh3 act as monodentate ligands to connect the rule to the data and decision in the question.

This matters because —h2o, oh- and nh3 act as monodentate ligands determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —h2o, oh- and nh3 act as monodentate ligands to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —H2O, OH- and NH3 act as monodentate ligands is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand why complexes with six-fold coordination have an octahedral shape, such as those formed by metal ions with H2O, OH- and NH3 as ligands.

Use —why complexes with six-fold coordination have an octahedral shape, such as those formed by metal ions with h2o, oh- and nh3 to connect the rule to the data and decision in the question.

This matters because —why complexes with six-fold coordination have an octahedral shape, such as those formed by metal ions with h2o, oh- and nh3 determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —why complexes with six-fold coordination have an octahedral shape, such as those formed by metal ions with h2o, oh- and nh3 to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Why complexes with six-fold coordination have an octahedral shape, such as those formed by metal ions with H2O, OH- and NH3 is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that transition metal ions may form tetrahedral complexes with relatively large ions such as Cl.

Use —transition metal ions may form tetrahedral complexes with relatively large ions such as cl- to connect the rule to the data and decision in the question.

This matters because —transition metal ions may form tetrahedral complexes with relatively large ions such as cl- determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —transition metal ions may form tetrahedral complexes with relatively large ions such as cl- to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Transition metal ions may form tetrahedral complexes with relatively large ions such as Cl- is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that square planar complexes are also formed by transition metal ions and that cis-platin is an example of such a complex which is used in cancer treatment where it is supplied as a single isomer and not in a mixture with the trans form.

Use —square planar complexes are also formed by transition metal ions and that cis-platin is an example of such a complex which to connect the rule to the data and decision in the question.

This matters because —square planar complexes are also formed by transition metal ions and that cis-platin is an example of such a complex which determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —square planar complexes are also formed by transition metal ions and that cis-platin is an example of such a complex which to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Square planar complexes are also formed by transition metal ions and that cis-platin is an example of such a complex which is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the terms ‘bidentate’ and ‘hexadentate’ in relation to ligands, and be able to identify examples such as NH2CH2CH2NH2 and EDTA4.

Use —the terms ‘bidentate’ and ‘hexadentate’ in relation to ligands to connect the rule to the data and decision in the question.

This matters because —the terms ‘bidentate’ and ‘hexadentate’ in relation to ligands determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the terms ‘bidentate’ and ‘hexadentate’ in relation to ligands to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The terms ‘bidentate’ and ‘hexadentate’ in relation to ligands is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that haemoglobin is an iron(II) complex containing a polydentate ligand and that ligand exchange occurs when an oxygen molecule bound to haemoglobin is replaced by a carbon monoxide molecule The structure of the haem group will not be assessed.

Use —haemoglobin is an iron(ii) complex containing a polydentate ligand and that ligand exchange occurs when an oxygen molecule to connect the rule to the data and decision in the question.

This matters because —haemoglobin is an iron(ii) complex containing a polydentate ligand and that ligand exchange occurs when an oxygen molecule determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —haemoglobin is an iron(ii) complex containing a polydentate ligand and that ligand exchange occurs when an oxygen molecule to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Haemoglobin is an iron(II) complex containing a polydentate ligand and that ligand exchange occurs when an oxygen molecule is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know the colours of the oxidation states of vanadium (+5, +4, +3 and +2) in its compounds.

Use —the colours of the oxidation states of vanadium (+5, +4, +3 and +2) in its compounds to connect the rule to the data and decision in the question.

This matters because —the colours of the oxidation states of vanadium (+5, +4, +3 and +2) in its compounds determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the colours of the oxidation states of vanadium (+5, +4, +3 and +2) in its compounds to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The colours of the oxidation states of vanadium (+5, +4, +3 and +2) in its compounds is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand redox reactions for the interconversion of the oxidation states of vanadium (+5, +4, +3 and +2), in terms of the relevant Eo values.

Use —redox reactions for the interconversion of the oxidation states of vanadium (+5, +4, +3 and +2), in terms of the relevant eo to connect the rule to the data and decision in the question.

This matters because —redox reactions for the interconversion of the oxidation states of vanadium (+5, +4, +3 and +2), in terms of the relevant eo determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —redox reactions for the interconversion of the oxidation states of vanadium (+5, +4, +3 and +2), in terms of the relevant eo to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Redox reactions for the interconversion of the oxidation states of vanadium (+5, +4, +3 and +2), in terms of the relevant Eo is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand, in terms of the relevant E values, that the dichromate(VI) ion, Cr2O2- i can be reduced to Cr3+ and Cr2+ ions using zinc in acidic conditions ii can be produced by the oxidation of Cr3+ ions using hydrogen peroxide in alkaline conditions (followed by acidification).

Use —understand, in terms of the relevant e values, that the dichromate(vi) ion, cr2o2- i can be reduced to cr3+ and cr2+ ions to connect the rule to the data and decision in the question.

This matters because —understand, in terms of the relevant e values, that the dichromate(vi) ion, cr2o2- i can be reduced to cr3+ and cr2+ ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —understand, in terms of the relevant e values, that the dichromate(vi) ion, cr2o2- i can be reduced to cr3+ and cr2+ ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Understand, in terms of the relevant E values, that the dichromate(VI) ion, Cr2O2- i can be reduced to Cr3+ and Cr2+ ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that dichromate(VI) ions can be converted into chromate(VI) ions through the equilibrium Cr2O7^2− + H2O ⇌ 2CrO4^2− + 2H+.

Use —dichromate(vi) ions can be converted into chromate(vi) ions through the equilibrium cr2o7^2− + h2o ⇌ 2cro4^2− + 2h+ to connect the rule to the data and decision in the question.

This matters because —dichromate(vi) ions can be converted into chromate(vi) ions through the equilibrium cr2o7^2− + h2o ⇌ 2cro4^2− + 2h+ determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —dichromate(vi) ions can be converted into chromate(vi) ions through the equilibrium cr2o7^2− + h2o ⇌ 2cro4^2− + 2h+ to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Dichromate(VI) ions can be converted into chromate(VI) ions through the equilibrium Cr2O7^2− + H2O ⇌ 2CrO4^2− + 2H+ is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Be able to record observations and write suitable equations for the reactions of Cr3+(aq), Mn2+(aq), Fe2+(aq), Fe3+(aq), Co2+(aq), Ni2+(aq), Cu2+(aq) and Zn2+(aq) with aqueous sodium hydroxide and aqueous ammonia, including in excess.

Use —record observations and write suitable equations for the reactions of cr3+(aq), mn2+(aq), fe2+(aq), fe3+(aq), co2+(aq) to connect the rule to the data and decision in the question.

This matters because —record observations and write suitable equations for the reactions of cr3+(aq), mn2+(aq), fe2+(aq), fe3+(aq), co2+(aq) determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —record observations and write suitable equations for the reactions of cr3+(aq), mn2+(aq), fe2+(aq), fe3+(aq), co2+(aq) to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Be able to write ionic equations to show the meaning of amphoteric behaviour, deprotonation and ligand exchange in the reactions in 17.22.

Use —write ionic equations to show the meaning of amphoteric behaviour, deprotonation and ligand exchange in the reactions to connect the rule to the data and decision in the question.

This matters because —write ionic equations to show the meaning of amphoteric behaviour, deprotonation and ligand exchange in the reactions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —write ionic equations to show the meaning of amphoteric behaviour, deprotonation and ligand exchange in the reactions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Understand that ligand exchange, and an accompanying colour change, occurs in the formation of: i [Cu(NH3)4(H2O)2]2+ from [Cu(H2O)6]2+ via Cu(OH)2(H2O)4 ii [CuCl4]2- from [Cu(H2O)6]2+ iii [CoCl4]2- from [Co(H2O)6]2+.

Use —ligand exchange, and an accompanying colour change, occurs in the formation of: i [cu(nh3)4(h2o)2]2+ from [cu(h2o)6]2+ via to connect the rule to the data and decision in the question.

This matters because —ligand exchange, and an accompanying colour change, occurs in the formation of: i [cu(nh3)4(h2o)2]2+ from [cu(h2o)6]2+ via determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —ligand exchange, and an accompanying colour change, occurs in the formation of: i [cu(nh3)4(h2o)2]2+ from [cu(h2o)6]2+ via to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Ligand exchange, and an accompanying colour change, occurs in the formation of: i [Cu(NH3)4(H2O)2]2+ from [Cu(H2O)6]2+ via is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand, in terms of the positive increase in ∆Ssystem, that the substitution of a monodentate ligand by a bidentate or hexadentate ligand leads to a more stable complex ion.

Use —understand, in terms of the positive increase in ∆ssystem, that the substitution of a monodentate ligand by a bidentate or to connect the rule to the data and decision in the question.

This matters because —understand, in terms of the positive increase in ∆ssystem, that the substitution of a monodentate ligand by a bidentate or determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —understand, in terms of the positive increase in ∆ssystem, that the substitution of a monodentate ligand by a bidentate or to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Understand, in terms of the positive increase in ∆Ssystem, that the substitution of a monodentate ligand by a bidentate or is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that transition metals and their compounds can act as heterogeneous and homogeneous catalysts.

Use —transition metals and their compounds can act as heterogeneous and homogeneous catalysts to connect the rule to the data and decision in the question.

This matters because —transition metals and their compounds can act as heterogeneous and homogeneous catalysts determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —transition metals and their compounds can act as heterogeneous and homogeneous catalysts to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Transition metals and their compounds can act as heterogeneous and homogeneous catalysts is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that a heterogeneous catalyst is in a different phase from the reactants and that the reaction occurs at the surface of the catalyst.

Use —a heterogeneous catalyst is in a different phase from the reactants and that the reaction occurs at the surface of to connect the rule to the data and decision in the question.

This matters because —a heterogeneous catalyst is in a different phase from the reactants and that the reaction occurs at the surface of determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —a heterogeneous catalyst is in a different phase from the reactants and that the reaction occurs at the surface of to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —A heterogeneous catalyst is in a different phase from the reactants and that the reaction occurs at the surface of is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

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

Use —understand, in terms of oxidation number, how v2o5 acts as a catalyst in the contact process to connect the rule to the data and decision in the question.

This matters because —understand, in terms of oxidation number, how v2o5 acts as a catalyst in the contact process determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —understand, in terms of oxidation number, how v2o5 acts as a catalyst in the contact process to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Understand, in terms of oxidation number, how V2O5 acts as a catalyst in the contact process is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand how a catalytic converter decreases carbon monoxide and nitrogen monoxide emissions from internal combustion engines by: i adsorption of CO and NO molecules onto the surface of the catalyst, resulting in the weakening of bonds and chemical reaction ii desorption of CO2 and N2 product molecules from the surface of the catalyst.

Use —how a catalytic converter decreases carbon monoxide and nitrogen monoxide emissions from internal combustion engines by: i to connect the rule to the data and decision in the question.

This matters because —how a catalytic converter decreases carbon monoxide and nitrogen monoxide emissions from internal combustion engines by: i determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —how a catalytic converter decreases carbon monoxide and nitrogen monoxide emissions from internal combustion engines by: i to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —How a catalytic converter decreases carbon monoxide and nitrogen monoxide emissions from internal combustion engines by: i is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know that a homogeneous catalyst is in the same phase as the reactants and appreciate that the catalysed reaction will proceed via an intermediate species.

Use —a homogeneous catalyst is in the same phase as the reactants and appreciate that the catalysed reaction will proceed via to connect the rule to the data and decision in the question.

This matters because —a homogeneous catalyst is in the same phase as the reactants and appreciate that the catalysed reaction will proceed via determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —a homogeneous catalyst is in the same phase as the reactants and appreciate that the catalysed reaction will proceed via to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —A homogeneous catalyst is in the same phase as the reactants and appreciate that the catalysed reaction will proceed via is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Understand the role of Fe2+ ions in catalysing the reaction between I− and S2O8^2− ions.

Use —the role of fe2+ ions in catalysing the reaction between i− and s2o8^2− ions to connect the rule to the data and decision in the question.

This matters because —the role of fe2+ ions in catalysing the reaction between i− and s2o8^2− ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the role of fe2+ ions in catalysing the reaction between i− and s2o8^2− ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The role of Fe2+ ions in catalysing the reaction between I− and S2O8^2− ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Know the role of Mn2+ ions in autocatalysing the reaction between MnO4− and C2O4^2− ions.

Use —the role of mn2+ ions in autocatalysing the reaction between mno4− and c2o4^2− ions to connect the rule to the data and decision in the question.

This matters because —the role of mn2+ ions in autocatalysing the reaction between mno4− and c2o4^2− ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the role of mn2+ ions in autocatalysing the reaction between mno4− and c2o4^2− ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The role of Mn2+ ions in autocatalysing the reaction between MnO4− and C2O4^2− ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

CORE PRACTICAL 14 The preparation of a transition metal complex.

Use —core practical 14 the preparation of a transition metal complex to connect the rule to the data and decision in the question.

This matters because —core practical 14 the preparation of a transition metal complex determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —core practical 14 the preparation of a transition metal complex to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —CORE PRACTICAL 14 The preparation of a transition metal complex is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.