CAIE A Level Chemistry 9701 · Group 17
Chlorine, bromine and iodine are the first three elements in Group 17. At room temperature, chlorine is a gas, bromine is a liquid and iodine is a solid. Compare the volatility and the bond strength of these three elements, and explain both trends in terms of the forces involved.
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.