Write the equation for the reaction of strontium with water, and state the trend in reactivity of Group 2 metals with water down the group.
[2 marks]
Total for this question: 2
Chemistry
Group 2, the alkaline earth metals
AQA 3.2.2
A-level Chemistry (7405) · exam-style practice, examiner-report intelligence and the tools that drill it.
Board and spec code confirmed against AQA 7405 · registry checked 2026-07-11How this checking works
The topic on one screen
- Group 2 metals react with water to give the hydroxide + hydrogen: M + 2H2O → M(OH)2 + H2. Reactivity increases down the group.
- Reactivity rises down the group because the outer electrons are further from the nucleus and more shielded, so they are lost more easily.
- Atomic radius increases down the group because each element has an extra occupied electron shell (not just 'more shielding').
- Hydroxide solubility INCREASES down the group; sulfate solubility DECREASES down the group (BaSO4 is essentially insoluble).
- Barium sulfate's insolubility makes it safe as a 'barium meal' — the toxic Ba2+ ions are not released.
- Uses: Mg to extract Ti; Ca(OH)2 to neutralise acidic soils; Mg(OH)2 and CaCO3 as antacids.
Where students actually lose marks
Explaining the increase in atomic radius down the group, 'more shielding' or 'more orbitals' alone were marked insufficient — you must say there is an extra electron shell.
June 2024 Paper 1 examiner report (Q09.1)
When barium reacts with dilute sulfuric acid the reaction slows quickly; very few said why — insoluble barium sulfate forms a layer on the metal and blocks further reaction.
June 2024 Paper 1 examiner report (Q09.3)
In reaction equations, watch the product: magnesium with water/steam trips students up, and the wrong formula (e.g. for magnesium phosphate) loses the balancing mark.
June 2023 Paper 1 examiner report (Q03.5)
Try it — exam-style
Easy
ORIGINAL
Medium
ORIGINAL · after June 2024 Paper 1 Q09.1
Explain why atomic radius increases down Group 2.
[2 marks]
Total for this question: 2
Easy
ORIGINAL
State the trend in solubility down Group 2 for (a) the hydroxides and (b) the sulfates.
[2 marks]
Total for this question: 2
Medium
ORIGINAL
Barium compounds are toxic, yet a suspension of barium sulfate is swallowed as a 'barium meal' before an X-ray. Explain why this is safe.
[2 marks]
Total for this question: 2
Medium
ORIGINAL · after June 2025 Paper 1 Q01.3
Suggest why magnesium hydroxide is safer than sodium hydroxide as a treatment for indigestion.
[1 mark]
Total for this question: 1
Hard
ORIGINAL · after June 2024 Paper 1 Q09.3
When barium is added to dilute sulfuric acid the reaction quickly slows down. Explain why.
[2 marks]
Total for this question: 2
Questions are written in the style of past AQA papers (source shown on each) — never copied from them.
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Group 2 marks are won on precise trend explanations — 'extra shell', not 'more shielding' — and that's exactly what I drill. Free intro call, then a free first lesson.