OCR A-Level Chemistry AS Breadth in chemistry (01), June 2022: Question 1

1 mark · Easy difficulty · Multiple Choice

Identify which substance forms a giant covalent lattice structure in the solid state from a given list of four substances.

Practise this question

Question

Multiple-choice question 1 asks: 'Which substance has a giant covalent lattice structure in its solid state?' Four options are given: A: potassium, B: silicon, C: sodium chloride, and D: water, followed by an answer box and an allocated mark of [1].
Question text

1 Which substance has a giant covalent lattice structure in its solid state?

A potassium

B silicon

C sodium chloride

D water

Your answer [1]

Mark scheme

Show the mark scheme Mark scheme table row showing Question 1 with correct answer B, awarded 1 mark with assessment objective AO1.1.

1 B 1 AO1.1

How to answer it

Giant Covalent Lattices & Solid Structures

📌 What this question tests

This question tests your ability to classify solid substances by their bonding and crystal lattice type (giant metallic, giant covalent, giant ionic, or simple molecular). It specifically assesses knowledge of Group 14 elemental structures (AO1.1 recall).

Question 1

Multiple Choice: Identifying Lattice Structures

✅ Correct Answer: B (silicon)

Silicon has a giant covalent lattice structure identical in geometry to diamond, where each silicon atom is tetrahedrally bonded to four other silicon atoms by strong covalent bonds throughout the entire structure.

Mark Scheme: Award 1 mark for option B [AO1.1].

💡 Key Knowledge: The Four Lattice Types

  • A: Potassium (K) → Metal = Giant metallic lattice (positive metal ions in a sea of delocalised electrons).
  • B: Silicon (Si) → Group 14 element = Giant covalent lattice (macromolecular).
  • C: Sodium chloride (NaCl) → Metal + Non-metal = Giant ionic lattice (oppositely charged ions: Na⁺ and Cl⁻).
  • D: Water (H₂O) → Ice = Simple molecular lattice (covalent bonds within molecules, but held together in the solid by weak intermolecular hydrogen bonds).

🧠 Exam Technique: Systematic Elimination

Always distinguish between type of bonding and crystal structure/lattice:

  1. Identify the elements: Metal only? Metal + Non-metal? Non-metals only?
  2. Eliminate metals ( K → metallic) and ionic salts ( NaCl → ionic).
  3. For covalent substances, ask: Does it form discrete small molecules or an infinite network? Water ( H₂O ) is simple molecular. Silicon ( Si , Group 14) forms an infinite 3D covalent network.

❌ Common Errors & Misconceptions

  • Confusing "Covalent Bonds" with "Giant Covalent Structure": Many students pick D (water) because they know water contains covalent bonds. However, solid ice is a simple molecular lattice, not a giant covalent one.
  • Forgetting Period 3 periodicity: Silicon is directly beneath Carbon in Group 14. Just like diamond, silicon forms 4 covalent bonds per atom in a giant macromolecular tetrahedral framework.

Topics

Module 2: Foundations in chemistry · Module 3: Periodic table and energy · 2.2 Electrons, bonding and structure · 3.1 The periodic table

Question and mark scheme from the OCR A-Level Chemistry examination, AS Breadth in chemistry (01), June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.