Pearson Edexcel International GCSE Chemistry 4CH1: Ionic, covalent and metallic bonding – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions cover sub-topics 1(f) Ionic bonding, 1(g) Covalent bonding and 1(h) Metallic bonding (points 1.37 to 1.54C) of the Pearson Edexcel International GCSE Chemistry (4CH1) specification, Issue 3 (September 2024). The qualification is untiered. Points 1.52C to 1.54C carry a C reference, so they are Paper 2 only; question 10 is labelled.

This set adds to the Principles of chemistry practice set and uses different questions. Learn the content first in the bonding study guide and the bonding revision notes. Course hub: Edexcel IGCSE Chemistry; printable checklist.

In the written answers below, dot-and-cross diagrams are shown in text. Brackets ( ) mark the overlap of two outer shells, where the shared pairs sit. In the exam, draw circles.

Questions

1. Calcium reacts with nitrogen to form an ionic compound.

(a) Describe how a calcium atom forms a calcium ion. Give the electronic configuration of the ion. [2] (b) State the charge on a nitride ion. Explain your answer in terms of electrons. [2]

2. Write the formula of each compound.

(a) aluminium sulfate [1] (b) ammonium carbonate [1] (c) iron(III) hydroxide [1] (d) lead(II) nitrate [1] (e) silver oxide [1]

3. Lithium reacts with nitrogen to form lithium nitride. Draw a dot-and-cross diagram to show the formation of lithium nitride from its atoms. Show outer electrons only. [3]

4. Magnesium oxide is used to line the inside of furnaces. Explain, in terms of structure and bonding, why magnesium oxide has a very high melting point. [3]

5. (a) State what is meant by a covalent bond. [1] (b) Explain, in terms of electrostatic attraction, why a covalent bond holds two atoms together. [2]

6. Draw a dot-and-cross diagram for each molecule. Show outer electrons only.

(a) nitrogen, N₂ [2] (b) ammonia, NH₃ [2] (c) ethene, C₂H₄ [2]

7. The table gives data for the halogens.

Halogen	Mr	Melting point / °C	Boiling point / °C
F₂	38	−220	−188
Cl₂	71	−102	−34
Br₂	160	−7	59
I₂	254	114	184

(a) Use the data to state the physical state of bromine at 25 °C. [1] (b) Explain the trend in boiling point from fluorine to iodine. [3] (c) A student writes: “When iodine boils, the bonds between the iodine atoms break.” Explain why the student is wrong. [2]

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

Substance	Melting point / °C	Conducts when solid?	Conducts when molten?
W	2050	no	yes
X	−23	no	no
Y	above 3500	no	no
Z	660	yes	yes

(a) Identify the type of structure of each substance. [4] (b) Explain why X has a low melting point. [2] (c) Explain why Y has a very high melting point. [2]

9. Diamond, graphite and C60 fullerene are all forms of carbon.

(a) Explain why C60 fullerene is soft but diamond is very hard. [3] (b) Explain why graphite is soft and slippery, so it can be used as a lubricant. [2] (c) Graphite conducts electricity but C60 fullerene is a poor conductor. Suggest why. [2]

10. (Paper 2 only) This question is about metals.

(a) Draw a labelled two-dimensional diagram to represent the metallic lattice in magnesium. [2] (b) Explain metallic bonding in terms of electrostatic attractions. [2] (c) Solid aluminium conducts electricity but solid aluminium oxide does not. Explain this difference. [2]

11. Carbon dioxide is a gas at room temperature. Silicon dioxide is a solid with a very high melting point.

(a) Draw a dot-and-cross diagram for a molecule of carbon dioxide. Show outer electrons only. [2] (b) Explain, in terms of structure and bonding, why carbon dioxide is a gas at room temperature but silicon dioxide has a very high melting point. [4] (c) Name a form of carbon that has the same type of structure as silicon dioxide, and state one physical property they share. [2]

Answers

1. (a) The calcium atom (2.8.8.2) loses its two outer electrons [1]. The ion is Ca²⁺ with configuration 2.8.8 [1]. (b) 3− [1]. Nitrogen (2.5) gains three electrons to fill its outer shell, so it has 7 protons and 10 electrons [1]. [4] Examiner insight: A charge needs both the number and the sign; “gains protons” or “loses neutrons” earns nothing because only electrons move.

2. (a) Al₂(SO₄)₃ [1] (b) (NH₄)₂CO₃ [1] (c) Fe(OH)₃ [1] (d) Pb(NO₃)₂ [1] (e) Ag₂O [1] [5] Examiner insight: Each formula is all-or-nothing: a missing bracket, as in AlSO₄ or Al₂SO₄₃, loses the mark even if the ion charges were worked out correctly.

3. Three lithium atoms each lose one electron (shown as dots), giving three [Li]⁺ ions [1]. The nitrogen atom gains three electrons to give [N]³⁻ with eight outer electrons: five crosses and three dots [1]. Square brackets and the correct charges on all four ions [1]. [3]

Li•   Li•   Li•   +   N (5 x)
          ->
[Li]+  [Li]+  [Li]+   [ N: 5 x + 3 • ]3-

Examiner insight: Drawing only one lithium ion is a common way to lose a mark; the number of ions drawn must match the formula Li₃N.

4. Magnesium oxide has a giant ionic lattice [1]. There are strong electrostatic attractions between the oppositely charged Mg²⁺ and O²⁻ ions [1]. There are many of these attractions throughout the lattice, so a lot of energy is needed to overcome them [1]. [3] Examiner insight: Any mention of molecules or intermolecular forces in an ionic answer contradicts the structure and usually costs the structure mark.

5. (a) A shared pair of electrons between two atoms [1]. (b) The shared pair of electrons (negative) [1] is attracted to the nuclei of both atoms (positive) [1]. [3] Examiner insight: For (b), “attraction between the atoms” does not score; name both the shared pair and the two nuclei.

6. (a) Three shared pairs between the two nitrogen atoms [1]; one lone pair on each nitrogen [1].

xx N (xxx •••) N ••

(b) Three shared pairs, one between N and each H [1]; one lone pair on nitrogen [1].

         xx
  H (•x) N (x•) H
         (x•)
          H

(c) Two shared pairs between the carbon atoms (a double bond) [1]; one shared pair between each C–H (each carbon bonded to two hydrogens), with no lone pairs [1]. (Left C = x, right C = o, H = •.) [6]

  H              H
 (•x)          (o•)
    C (xx oo) C
 (•x)          (o•)
  H              H

Examiner insight: The bonding pairs and the lone pairs score separate marks, so a diagram with the right shared pairs but missing lone pairs still earns one of the two marks.

7. (a) Liquid: 25 °C is above its melting point (−7 °C) and below its boiling point (59 °C) [1]. (b) The relative molecular mass increases from F₂ to I₂ [1], so the intermolecular forces become stronger [1], and more energy is needed to overcome them [1]. (c) Boiling only overcomes the weak intermolecular forces between I₂ molecules [1]. The covalent bond within each I₂ molecule is not broken; the vapour is still I₂ [1]. [6] Examiner insight: In (b), “the bonds get stronger” is ambiguous and does not score; the answer must say intermolecular forces.

8. (a) W: giant ionic [1]. X: simple molecular [1]. Y: giant covalent [1]. Z: metallic (giant metallic lattice) [1]. (b) Only weak intermolecular forces between the molecules have to be overcome [1], so little energy is needed [1]. (c) Many strong covalent bonds throughout the structure [1] must be broken, which needs a lot of energy [1]. [8] Examiner insight: “Covalent” on its own for X or Y scores nothing in (a): the mark needs simple molecular or giant covalent.

9. (a) C60 is made of separate molecules (simple molecular) [1]. Only weak intermolecular forces hold the molecules together, so they are easily separated [1]. In diamond each carbon is joined to four others by strong covalent bonds in a rigid giant three-dimensional network [1]. (b) Graphite has layers of carbon atoms held together by weak forces between the layers [1], so the layers can slide over each other [1]. (c) Graphite has delocalised electrons (one per carbon) that can move along the layers through the whole giant structure [1]. In C60 the electrons cannot move from one molecule to the next [1]. [7] Examiner insight: In (b), saying the covalent bonds in graphite are weak contradicts its high melting point and does not score; the weak forces are between the layers.

10. (a) Regular, closely packed rows of positive ions, labelled (for example 2+) [1]; electrons drawn between the ions, labelled delocalised electrons [1].

 (2+) e- (2+) e- (2+)
 e- (2+) e- (2+) e-
 (2+) e- (2+) e- (2+)

(b) Electrostatic attraction between the positive metal ions [1] and the delocalised electrons [1]. (c) Aluminium has delocalised electrons that are free to move through the structure and carry charge [1]. In solid aluminium oxide the ions are held in fixed positions in the lattice and cannot move [1]. [6] Examiner insight: An unlabelled diagram, or one labelled “atoms” or “protons”, loses marks in (a); both labels, positive ions and delocalised electrons, are needed.

11. (a) Two shared pairs between carbon and each oxygen (two double bonds) [1]; two lone pairs on each oxygen [1]. (C = x, O = o.)

  oo                oo
  O  (oo xx) C (xx oo)  O
  oo                oo

(b) Carbon dioxide is simple molecular [1], with weak intermolecular forces that need little energy to overcome [1]. Silicon dioxide is giant covalent [1], so many strong covalent bonds must be broken to melt it, needing a lot of energy [1]. (c) Diamond (graphite also accepted) [1]. Shared property: high melting point (or solid at room temperature) [1]. [8] Examiner insight: A comparison question needs both substances explained; a full answer about carbon dioxide alone can reach only half the marks in (b).

Where marks are usually lost

• Giving a charge without its sign, such as “3” for the nitride ion.
• Omitting brackets in formulae with more than one group ion.
• Drawing too few positive ions in an ionic dot-and-cross diagram.
• Leaving brackets or charges off the ions in an ionic diagram.
• Missing lone pairs on nitrogen, oxygen or a halogen in a covalent diagram.
• Writing “bonds” instead of “intermolecular forces” for simple molecular substances.
• Calling C60 a giant covalent structure.
• Writing “covalent” without saying simple molecular or giant covalent.
• In metals, describing the particles as atoms or protons instead of positive ions.
• Explaining only one substance in a “compare” question.

Next steps

• Bonding revision notes
• Bonding study guide
• Principles of chemistry practice questions
• Chemical formulae, equations and calculations practice
• Free 4CH1 all-topics diagnostic
• Edexcel IGCSE Chemistry course hub
• Printable Edexcel IGCSE Chemistry checklist
• Book a free trial class

Official syllabus

Pearson Edexcel International GCSE in Chemistry (4CH1) specification, Issue 3, September 2024, published by Pearson Education Limited – Topic 1 Principles of chemistry, sub-topics (f) Ionic bonding, (g) Covalent bonding and (h) Metallic bonding, points 1.37 to 1.54C.