CAIE A Level Chemistry 9701 · Chemistry of transition elements
The chromium(III) ion, , forms a violet complex ion in aqueous solution. The calcium ion, , forms a colourless solution.
Compare the chromium(III) ion with the calcium ion in terms of the definition of a transition element. Explain why chromium(III) forms a coloured complex ion but calcium does not.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.