CAIE A Level Chemistry 9701 · Group 2
The thermal stability of the nitrates and carbonates of the Group 2 elements increases down the group from magnesium to barium.
Explain this trend in terms of the polarising power of the cation and the polarisation of the large anion.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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