A-LevelChemistryChemical periodicity9701/21 · Oct/Nov 2020 · Q16 Marks
The graph shows the first ionisation energies of some of the elements in Group 2. [Figure 1.1]
- (a)Write an equation for the first ionisation energy of Mg. Include state symbols.[1]
- (b)Explain the observed trend in first ionisation energies down Group 2.[3]
- (c)The second ionisation energy of Be is 1757 kJ mol⁻¹. Explain why the second ionisation energy of Be is higher than the first ionisation energy of Be.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.
- [1] Mg(g) → Mg+(g) + e(-)
- [1] M1: distance between nucleus and outer e¯ increases OR outer electron removed from higher energy shell
- [1] M2: increased shielding
- [1] M3: decreased nuclear attraction
- [1] M1: greater nuclear attraction
- [1] M2: (2nd/2s) electron being removed from smaller (ion)
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