Typical properties — AQA GCSE Chemistry
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Typical properties explained
Typical properties covers 2 specification points, including Many transition elements have ions with… and Students should be able to exemplify these….
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Open a point below for its explanation and revision guidance.
Many transition elements have ions with different charges, form coloured compounds and are useful as catalysts.
This statement covers three typical properties of transition elements. First, many form ions with different charges, known as variable oxidation states; iron forms Fe²⁺ and Fe³⁺, and copper forms Cu⁺ and Cu²⁺. Second, transition element compounds are often coloured: copper(II) sulfate is blue, iron(III) chloride is yellow-brown and potassium manganate(VII) is purple. Third, transition elements and their compounds are useful catalysts: iron catalyses the Haber process, nickel catalyses hydrogenation and manganese(IV) oxide catalyses the decomposition of hydrogen peroxide. You do not need to explain why these properties occur at GCSE. When answering, name the element or compound, state the property and give a specific example.
Students should be able to exemplify these general properties by reference to compounds of Cr, Mn, Fe, Co, Ni, Cu.
Transition metals show general properties such as forming ions with different charges, forming coloured compounds, and acting as catalysts. To exemplify these, you must recall specific compounds of Cr, Mn, Fe, Co, Ni and Cu. For example, chromium forms orange potassium dichromate(VI), K₂Cr₂O₇. Iron forms ions with different charges: iron(II) sulfate, FeSO₄, is pale green, while iron(III) chloride, FeCl₃, is yellow-brown. Manganese(IV) oxide, MnO₂, catalyses the decomposition of hydrogen peroxide. Cobalt(II) chloride, CoCl₂, is pink in aqueous solution. Nickel(II) sulfate, NiSO₄, forms green solutions. Hydrated copper(II) sulfate, CuSO₄·5H₂O, is blue. You must link each compound to a specific property, such as colour or catalytic activity.
Your focus
- Describe that many transition elements form ions with different charges.
- Describe that many transition element compounds are coloured.
- Describe that transition elements and their compounds are useful as catalysts, giving named examples.
Show all 6 objectives
- Name at least one compound of each of Cr, Mn, Fe, Co, Ni and Cu.
- Link each named compound to a general transition-metal property such as colour or catalysis.
- Write correct formulas and identify ions with different charges for the chosen compounds.
Typical properties exam tips
Marking Points
- Many transition elements form ions with different charges, for example Fe²⁺ and Fe³⁺ or Cu⁺ and Cu²⁺.
- Transition element compounds are often coloured, such as blue copper(II) sulfate and purple potassium manganate(VII).
- Transition elements and their compounds act as catalysts, for example iron in the Haber process.
- Nickel is used as a catalyst in the hydrogenation of alkenes to alkanes.
- Manganese(IV) oxide catalyses the decomposition of hydrogen peroxide.
- Names a compound of Cr, Mn, Fe, Co, Ni or Cu and correctly links it to a general transition-metal property such as colour, forming ions with different charges, or catalysis.
- Gives the correct formula or name for the chosen compound, for example K₂Cr₂O₇, MnO₂, FeSO₄, CoCl₂, NiSO₄ or hydrated CuSO₄.
- States the charge of the transition metal ion where the property depends on it, for example Fe in FeSO₄ is 2⁺ and Fe in FeCl₃ is 3⁺.
- Describes the observed property accurately, for example 'orange solution' or 'catalyses decomposition of H₂O₂'.
- Uses compounds of all six listed transition metals across examples to show the properties are general.
Examiner Tips
- 💡For each typical property, prepare one named example so you can answer quickly and precisely.
- 💡When describing variable charges, give two ions of the same element to show the difference clearly.
- 💡Learn one clear compound example per metal (Cr, Mn, Fe, Co, Ni, Cu) so you can answer quickly under time pressure.
- 💡When asked to 'exemplify', give the compound name or formula plus the property in the same sentence.
Common Mistakes
- Stating that all transition element compounds are coloured: correct this by saying many are coloured, since some such as zinc compounds are white.
- Giving a catalyst without naming the reaction: correct this by stating both, for example iron catalyses the Haber process.
- Writing ion charges without superscript signs: correct this by using notation such as Fe²⁺ and Fe³⁺.
- Naming a compound but not linking it to a property. Correction: always state the property, for example 'hydrated CuSO₄ is blue because transition metal compounds are coloured'.
- Stating that anhydrous copper(II) sulfate is blue. Correction: specify that hydrated copper(II) sulfate or aqueous copper(II) sulfate is blue, as the anhydrous form is white.
- Confusing iron(II) and iron(III) compounds. Correction: check the Roman numeral and the charge; Fe²⁺ compounds are usually pale green and Fe³⁺ compounds are often yellow-brown.