Complete the table using ticks (√) to indicate whether the sign of each type of energy change, under standard conditions, is always positive, always negative or could be either positive or negative. [Table with columns: 'energy change', 'always positive', 'always negative', 'either positive or negative' and rows: 'electron affinity', 'enthalpy change of atomisation', 'ionisation energy', 'lattice energy']

1. (a)Complete the table using ticks (√) to indicate whether the sign of each type of energy change, under standard conditions, is always positive, always negative or could be either positive or negative.[2]
2. (b)(i)Explain why ΔH4 is greater than ΔH3.[1]
3. (b)(ii)What names are given to the enthalpy changes ∆H6 and ΔΗ7? ΔH6 ΔH7[1]
4. (c)Chlorine is in Group 17. Suggest the trend in the first electron affinity of the elements in Group 17. Explain your answer.[2]
5. (d)The equation for the formation of magnesium oxide from its elements is shown. Mg(s) + ½O₂(g) → MgO(s) ΔH° = −602 kJ mol⁻¹ substance S°/J K⁻¹ mol⁻¹ Mg(s) 32.7 O₂(g) 205 MgO(s) 26.9 Use the equation and the data given in the table to calculate ΔG° for the reaction at 25°C. ΔG = units[4]

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