Ionic bondingAQA A-Level Chemistry: Subtopic test

1. 1
   Magnesium oxide is used to line industrial furnaces because it has a very high melting point. Aluminium sulfate is used to treat drinking water.

   (a)

   What is the charge on the ion formed by magnesium, a Group 2 element?

   [1 mark]

   • A1+
   • B1−
   • C2+
   • D2−

   (b)

   What is the formula of aluminium sulfate? The ions are Al³⁺ and SO₄²⁻.

   [1 mark]

   • AAlSO₄
   • BAl₂SO₄
   • CAl(SO₄)₃
   • DAl₂(SO₄)₃

   (c)

   Describe the bonding in magnesium oxide.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A garden fertiliser is a mixture of ammonium nitrate and ammonium sulfate. The manufacturer lists the ingredients using their formulas.

   (a)

   What is the formula of ammonium sulfate? The ions are NH₄⁺ and SO₄²⁻.

   [1 mark]

   • A(NH₄)₂SO₄
   • BNH₄SO₄
   • C(NH₄)₂(SO₄)₂
   • DNH₄(SO₄)₂

   (b)

   How many ions are there in one formula unit of ammonium sulfate?

   [1 mark]

   • A2
   • B3
   • C4
   • D15

   (c)

   Explain why the formula of ammonium sulfate contains two ammonium ions for every sulfate ion.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A geologist records three minerals in a rock sample: bauxite, which contains aluminium oxide; limestone, which contains calcium carbonate; and a salt deposit containing calcium nitrate.

   (a)

   Use the position of the elements in the Periodic Table to predict the charge on the ions in aluminium oxide, and construct its formula.

   [3 marks]

   (b)

   Explain why the formula of calcium nitrate is written Ca(NO₃)₂ and not CaNO₃₂.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A student is revising ionic compounds. She writes: 'Magnesium oxide, MgO, is made of molecules. A magnesium atom gives two electrons to an oxygen atom to form one MgO molecule, held together by a single bond.' She is also asked to construct formulas using the Periodic Table and the compound ions ammonium, NH₄⁺, hydroxide, OH⁻, and carbonate, CO₃²⁻.

   (a)

   Predict the charges on the ions present in each of the following compounds, and construct the formula of each: (i) magnesium nitride; (ii) barium hydroxide; (iii) ammonium carbonate.

   [6 marks]

   (b)

   Evaluate the student's statement about magnesium oxide. State what is correct, what is wrong, and give a correct description of the structure and bonding.

   [6 marks]

   Total for question 4: 12 marks

End of questions