What you’ll learn3 learning objectivesChoose one objective for a focused lesson, or study the complete topic.11.1.1Colours and the trend in volatility• Describe the colours and the trend in volatility of chlorine, bromine and iodineSyllabus objective11.1.2Trend in the bond strength of the halogen• Describe/explain: the trend in the bond strength of the halogen moleculesSyllabus objective11.1.3The volatility of the elements• Interpret the volatility of the elements in terms of instantaneous dipole–induced dipole forcesSyllabus objective