Ionic Bonding (Edexcel IGCSE Science (Double Award): Chemistry)

What is the formula of potassium sulfate?

The diagram shows the arrangement of electrons in an atom of calcium and in an atom of chlorine.

Describe, in terms of electrons, what happens when calcium reacts with chlorine to form the ionic compound calcium chloride, CaCl₂

Describe tests to show that an aqueous solution of calcium chloride contains calcium ions and chloride ions.

calcium ions: ...................................................................... chloride ions:  ......................................................................

Solid calcium chloride does not conduct electricity. Aqueous solutions of calcium chloride do conduct electricity. A student uses this method to investigate how the conductivity of a solution changes when calcium chloride is dissolved in pure water.

  Step 1 add 100 cm³ of pure water to a beaker

Step 2 add one spatula of solid calcium chloride to the beaker Step 3 stir the solution
Step 4 measure the conductivity of the solution
Step 5 repeat until nine spatulas of solid calcium chloride have been added

  The table shows the student’s results.

i) Plot the results on the grid and draw two straight lines of best fit. Ignore the anomalous result.

(3)

ii) State the trend shown on the graph for the first six spatulas of calcium chloride.

(1)

iii) Suggest an error the student could have made to cause the anomalous result.

(1)

Describe another way to make solid calcium chloride conduct electricity.

The table below shows the properties of four substances, W, X, Y and Z.

Use the information in the table to identify the substance that is an ionic compound.

The formation of ions and covalent bonds involves electrons.

The table gives the electronic configurations of atoms of hydrogen, lithium and chlorine.

Describe the different roles of electrons in the formation of

• ions in lithium chloride

• covalent bonds in hydrogen chloride

Explain why lithium chloride has a higher melting point than hydrogen chloride.

Refer to structure and bonding in your answer.

Which of the following dot-and-cross diagrams shows the correct arrangement of electrons in lithium sulfide?

This is a question about metals and their compounds.

State one property of metals.

Mercury is the only metal that is liquid at room temperature.

 Describe the difference in the movement of particles in liquid mercury and in a solid metal.

Magnesium is a metal that burns in air.

 i) State one observation made during the combustion of magnesium metal.

 (1)

 ii) State one chemical property of the product of combustion that can be used to classify magnesium as a metal.

 (1)

In the absence of air, magnesium reacts with sulfur to form the ionic compound magnesium sulfide, MgS

 i) Give a reason why the reaction needs to be done in the absence of air. 

(1)

ii) Describe, in terms of electrons, the formation of the ions in magnesium sulfide.

 Give the charges on the ions.

 (3)

 iii) Explain why magnesium sulfide has a very high melting point.

 (3)

iv) Magnesium sulfide reacts with hydrochloric acid to form magnesium chloride and hydrogen sulfide gas, H₂S

 Give the chemical equation for this reaction.

 (2)

Which of the statements describes ionic bonding?

The diagram shows the electronic configurations of an atom of lithium and an atom of oxygen.

Which statement is not correct about the changes in electronic configuration that occur when lithium and oxygen react to form lithium oxide, Li₂O?