AQA A-Level Chemistry - Group 2 Questions and Answers

AQA A-Level Chemistry - Group 2
Questions and Answers
Explain the trend in atomic radius down group 2 – answer Increases down group.

Explain the trend in 1st ionisation energy down group 2 - answer-Decreases down
group.
-More shielding, weaker attraction as nucleus and outer e- further apart.
- Easier to remove outer e- (less energy).

Explain the trend in melting points down group 2 - answer-Generally decrease down
group (not Mg).
-Larger ions, distance between + metal nuclei and delocalised e- is greater.
-Less energy to break bonds.

Explain the trend in solubilities down group 2 - answer-Hydroxides, increase down
group,
-Sulfates, decrease down group.

Describe how you would test for the presence of sulfate ions - answer1. Add HCl
(removed carbonates whcih may give a false +).
2. Add BaCl2, observe white ppt;
Ba^2+(aq) + SO4^2-(aq) -> BaSO4(s)

What is the use of in medicine BaSO4? - answer-Barium Meal (X-ray)
-ID's issues with digestion

BaSO4 is toxic so why can it be used in medicine? - answerIt is insoluble

What is Mg(OH)2 used for? - answerAntacids

What is Ca(OH)2 used for? - answerAcidic soils (neutralise)

Explain the trend in reactivity down group 2 - answer-Reactivity with water increases
down group.
-Atomic radii increases, easier to remove outer e- as they're further from the nucleus
(more shielding).

Write an equation for the reaction of Sr with water - answerSr(s) + 2H2O(l) -> Sr(OH)
(aq) + H2(g)

Write an equation for the reaction of Mg with water - answerMg + 2H2O -> Mg(OH)2 +
H2