CAIE A Level Chemistry 9701 · Group 17
Table 1 shows some physical properties of chlorine, bromine and iodine.
| Halogen | Boiling point / °C | Bond dissociation energy / kJ mol⁻¹ |
|---|---|---|
| Chlorine, Cl₂ | –34 | 242 |
| Bromine, Br₂ | 59 | 193 |
| Iodine, I₂ | 184 | 151 |
Compare the volatility and the bond strength of these three elements. Explain the trends in terms of the intermolecular forces between the molecules and the bonding within the molecules.
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.