What you’ll learn5 learning objectivesChoose one objective for a focused lesson, or study the complete topic.23.1.1Terms• Define/use:: (a) enthalpy change of atomisation, ΔHat; (b) lattice energy, ΔHlatt (the change from gas phase ions to solid lattice)Syllabus objective23.1.2Terms: first electron affinity, EA• (a) define and use the term first electron affinity, EA: (b) explain the factors affecting the electron affinities of elements; (c) describe and explain the trends in the electron affinities of the Group 16 and Group 17 elementsSyllabus objective23.1.3Born–Haber cycles for ionic solids• Construct/use: Born–Haber cycles for ionic solids (limited to +1 and +2 cations, –1 and –2 anions)Syllabus objective23.1.4Calculations: Born–Haber cycles• Calculate: Born–Haber cyclesSyllabus objective23.1.5Explain, in qualitative terms, the effect• Explain, in qualitative terms, the effect of ionic charge and of ionic radius on the numerical magnitude of a lattice energySyllabus objective