Copper and potassium are both metals. Explain why copper is classed as a transition element but potassium is not, and state two properties that are typical of transition elements.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Copper lies in the d‑block of the periodic table, i.e. it has partially filled d orbitals, whereas potassium is in Group I of the s‑block and has a filled s orbital only. Therefore copper is a transition element and potassium is not.
Typical properties of transition elements are:
1. They form coloured compounds or ions.
2. They can act as catalysts and form ions with variable oxidation states.
Typical properties of transition elements are:
1. They form coloured compounds or ions.
2. They can act as catalysts and form ions with variable oxidation states.
Examiner tips
- Use the term "d‑block" and "s‑block" to show knowledge of the periodic table; mention partially filled d orbitals for copper.
- State two properties in separate bullet points; include both colour and variable oxidation states or catalytic activity.
Common mistakes
- Confusing potassium with a transition element by citing its reactivity; failing to mention the d‑block. Not specifying that copper has partially filled d orbitals. Giving only one property or mixing up properties of non‑transition metals.
Mark scheme (4 marks)
- Copper is in the d-block / middle section of the periodic table, whereas potassium is in Group I / s-block
- Transition elements form coloured compounds / ions
- Transition elements can act as catalysts
- Transition elements form ions with variable / different oxidation states
Key terms in this question
Related
- All Cambridge International IGCSE Chemistry (0620) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →