Group 1 and 2 elements and their compoundsEdexcel A-Level Chemistry: Subtopic test

1. 1
   The first ionisation energies of three Group 2 elements are: magnesium 738 kJ mol⁻¹, calcium 590 kJ mol⁻¹ and barium 503 kJ mol⁻¹.

   (a)

   Which value is the most likely first ionisation energy of strontium?

   [1 mark]

   • A453 kJ mol⁻¹
   • B549 kJ mol⁻¹
   • C612 kJ mol⁻¹
   • D738 kJ mol⁻¹

   (b)

   Which statement explains why barium is more reactive than magnesium?

   [1 mark]

   • ABarium atoms lose their outer electrons more easily because the outer electrons are further from the nucleus and more shielded
   • BBarium atoms have more protons, so they attract their outer electrons more strongly
   • CBarium has a higher first ionisation energy
   • DBarium ions are smaller than magnesium ions

   (c)

   Explain the trend in first ionisation energy down Group 2.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A technician investigates the reactions of Group 2 oxides and hydroxides with water and with dilute acids.

   (a)

   Calcium oxide is added to water. Which is the most likely pH of the resulting solution, and why?

   [1 mark]

   • ApH 7, because calcium oxide does not react with water
   • BpH 2, because an acid is formed
   • CpH 7, because a neutral salt is formed
   • DpH about 12, because calcium hydroxide forms and releases hydroxide ions

   (b)

   Which Group 2 hydroxide is the least soluble in water?

   [1 mark]

   • ABa(OH)₂
   • BSr(OH)₂
   • CMg(OH)₂
   • DCa(OH)₂

   (c)

   Write the equation for the reaction of magnesium oxide with dilute hydrochloric acid, and the equation for the reaction of calcium hydroxide with dilute nitric acid.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student heats samples of Group 1 and Group 2 nitrates and carbonates strongly in a hard glass test tube and records the changes.

   (a)

   Write the equation for the thermal decomposition of magnesium nitrate and state the colour of the gas given off.

   [3 marks]

   (b)

   Barium carbonate needs a much higher temperature to decompose than magnesium carbonate. Explain why.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   An analyst is asked to identify unlabelled white solids, each a compound of a Group 1 or Group 2 metal, using flame tests, thermal decomposition and solubility tests.

   (a)

   Compare the thermal decomposition of the nitrates and carbonates of Group 1 and Group 2. Explain the differences in terms of cation size and charge, and write the equation for the decomposition of lithium nitrate.

   [6 marks]

   (b)

   Describe how a flame test is carried out, give the flame colours of at least three named metal ions and explain how flame colours arise. State how adding dilute sulfuric acid to aqueous solutions could distinguish a barium compound from a calcium compound.

   [6 marks]

   Total for question 4: 12 marks

End of questions