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Topic 2: Bonding, Structure & Properties — Exam Practice

AQA GCSE Chemistry (8462) • Paper 1 • Structured Questions

📝 Exam Practice

Topic 2: Bonding & Properties Exam Practice

Test your knowledge with exam-style questions from past AQA GCSE Chemistry papers. Complete the multiple choice questions, then attempt the structured questions and check your answers against the mark scheme.

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📋 Structured Questions

These questions are typical of Paper 1. Attempt each question on paper, then click "Show Mark Scheme" to check your answer.

Question 1: Alloys — Conductivity

2 marks

Electrical wires are usually made of pure metals and not alloys, because pure metals are better electrical conductors.

(a) Suggest why alloys do not conduct electricity as well as pure metals. Answer in terms of structure and bonding. [2]

Show Mark Scheme
  • In alloys, different sized atoms distort the layers / structure [1]
  • The movement of delocalised electrons is restricted [1]
Examiner tip: This is a "suggest" question — examiners want you to apply your knowledge of metallic bonding to a new context. Link the distorted structure to the restricted movement of electrons. Don't just repeat the alloy hardness answer about layers sliding.

Question 2: Polymers

2 marks

Polymer B is a thermosoftening polymer which melts when heated.

(a) Explain why some polymers do not melt when heated. [2]

Show Mark Scheme
  • There are cross-links / covalent bonds between the polymer chains [1]
  • Too much energy is needed to overcome the cross-links / covalent bonds between chains [1]
Examiner tip: These are thermosetting polymers. The key distinction is the cross-links between chains — thermosoftening polymers only have weak intermolecular forces between chains, so they can melt.

Question 3: Giant Covalent Structures

3 marks

This question is about different forms of carbon.

(a) Explain why diamond has a very high melting point. [3]

Show Mark Scheme
  • It has a giant structure / macromolecular / giant lattice [1]
  • It has covalent bonds [1]
  • The covalent bonds are strong / many covalent bonds must be broken / a lot of energy is required to break the bonds [1]
Examiner tip: Always state the type of structure (giant covalent) first, then describe the bonds, and finally explain that lots of energy is needed. Missing any of these three steps costs you a mark.

Question 4: Metallic Bonding

3 marks

(a) Describe how metals conduct electricity. Answer in terms of electrons. [3]

Show Mark Scheme
  • Metals have delocalised / free electrons [1]
  • The electrons carry electrical charge [1]
  • The electrons move through the metal / structure [1]
Examiner tip: The key term is delocalised electrons — do not just say "free electrons" without explaining what that means. You must state that the electrons carry charge and that they move through the structure. Simply saying "metals have free electrons" only scores 1 mark.

Question 5: Alloys — Hardness

3 marks

Pure iron is too soft for many uses.

(a) Explain why mixing iron with other metals makes alloys which are harder than pure iron. [3]

Show Mark Scheme
  • The alloy has different sized atoms / ions [1]
  • The layers are distorted [1]
  • The layers cannot easily slide over each other [1]
Examiner tip: Use the key phrase "layers cannot slide" — this is what examiners are looking for. Also mention that the different sized atoms disrupt the regular arrangement.

Question 6: States of Matter

4 marks

Methane is a gas at room temperature but poly(ethene) is a solid at room temperature.

(a) Explain why methane and poly(ethene) exist in different states at room temperature. [4]

Show Mark Scheme
  • Methane has much smaller molecules [1]
  • So it has weaker intermolecular forces [1]
  • The intermolecular forces need less energy to overcome [1]
  • So the boiling/melting point is lower and methane is a gas [1]
Examiner tip: Do not refer to breaking covalent bonds — this is a common mistake. You must talk about overcoming intermolecular forces, not covalent bonds within molecules.

Question 7: Bonding, Structure & Properties ⭐ Extended Response

6 marks

A student is provided with data for three unknown solid substances: X, Y, and Z.
Substance X: High melting point, conducts electricity when molten, brittle.
Substance Y: Low melting point, does not conduct electricity, soft.
Substance Z: Very high melting point, does not conduct electricity, very hard.

(a) Based on the data, determine the types of bonding present in substances X, Y, and Z, and justify your choices by linking their properties to their structure. [6]

Show Mark Scheme

Level 3 (5–6 marks): Clear identification and justification of each bonding type with direct reference to structural properties. Logical reasoning demonstrated consistently.

Level 2 (3–4 marks): Correct bonding types identified with some valid explanation linking properties to structure.

Level 1 (1–2 marks): Simple identification of bonding types with limited or no structural explanation.

Indicative content:

  • Substance X (Ionic): giant ionic lattice; high melting point due to strong electrostatic forces between oppositely charged ions; conducts when molten because ions are free to move and carry charge
  • Substance Y (Simple covalent): simple molecules; low melting point due to weak intermolecular forces between molecules; does not conduct as no free electrons or ions
  • Substance Z (Giant covalent): giant covalent lattice; very high melting point due to strong covalent bonds throughout the structure; does not conduct (no delocalised electrons)
Examiner tip: When discussing simple molecular substances (Y), be extremely careful to state that weak intermolecular forces are overcome when melting — not the strong covalent bonds inside the molecules. This is the most common error on this question type.

Question 8: Practical Skills — Testing Electrical Conductivity 🔬

4 marks

A student tests the electrical conductivity of four substances: sodium chloride (solid), sodium chloride (molten), sugar (solid), and copper metal.

(a) Predict and explain which substances would conduct electricity. [4]

Show Mark Scheme
  • Solid NaCl: does not conduct — ions are held in fixed positions in the lattice and cannot move [1]
  • Molten NaCl: conducts — ions are free to move and carry charge [1]
  • Sugar: does not conduct — simple molecular substance with no free ions or electrons [1]
  • Copper: conducts — metallic bonding gives delocalised electrons that are free to flow [1]
Examiner tip: Always explain why a substance conducts — don't just say "it conducts." You must state what carries the charge: free ions (ionic molten/dissolved) or delocalised electrons (metals/graphite).
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