Topic 2.4.4: Lattice Structure
Past Paper Examination Questions
15 Questions
Paper 2 & 4 Style
30 Marks Total
Time: ~25 minutes
Section A: Structure Descriptions (10 marks)
Describe the structure of sodium chloride.
⚠️ Examiner Trap:
Students often forget to mention "giant" - this is a KEYWORD that examiners look for!
Define the term "lattice structure".
⚠️ Examiner Trap:
Don't just say "organized" - you need "regular" and "repeating".
Describe the structure of magnesium oxide, MgO.
⚠️ Examiner Trap:
Don't forget the charge ratio! Mg²⁺ and O²⁻ are 1:1 despite different charges.
State two features of a giant ionic structure.
⚠️ Examiner Trap:
Be specific! "Strong bonds" is too vague - name the TYPE of force.
Calcium fluoride, CaF₂, has a giant ionic structure. Describe this structure in terms of the particles present and the forces between them.
⚠️ Examiner Trap:
Notice the formula! There are TWICE as many F⁻ as Ca²⁺ ions. The ratio matters!
Section B: Forces in Lattices (9 marks)
Name the type of force holding the ions together in sodium chloride.
⚠️ Examiner Trap:
Don't say "ionic bond" - examiners want the PHYSICS term!
Explain why a large amount of energy is needed to break down an ionic lattice.
⚠️ Examiner Trap:
You must mention BOTH "strong" and "many" - one word alone = 0 marks!
Potassium bromide has a lattice structure. Explain why it has a high melting point.
⚠️ Examiner Trap:
The question asks WHY - link the structure to the property!
State the type of bonding in lithium oxide and describe the forces involved.
⚠️ Examiner Trap:
Name the bonding TYPE first, then describe the FORCE.
Which is stronger: the forces in a giant ionic lattice or the forces between simple molecules?
⚠️ Examiner Trap:
Easy marks - but explain WHY if asked!
Section C: Visual Identification (11 marks)
Identify which diagram below shows an ionic lattice structure.
Which diagram shows an ionic lattice?
Diagram A
(Separate molecules)
Diagram B
(Alternating ions)
Diagram C
(Covalent network)
⚠️ Examiner Trap:
Look for ALTERNATING colors (different ions) and REGULAR spacing!
The diagram shows part of a crystal lattice. Identify the particles labeled X and Y.
Part of a crystal lattice structure:
Note the different sizes of particles X and Y
⚠️ Examiner Trap:
SIZE matters! Larger sphere = anion (gained electrons), smaller = cation.
Draw a 2D diagram to show the arrangement of ions in a small section of a sodium chloride crystal. Use ⊕ for Na⁺ and ⊖ for Cl⁻.
Drawing space - use the symbols provided in the question
⚠️ Examiner Trap:
Must show at least 4 ions in a regular pattern - random = 0 marks!
Look at the diagram of a lattice structure. Suggest why the ions are arranged in this regular pattern.
Lattice structure showing ion arrangement:
Regular, alternating pattern of positive and negative ions
⚠️ Examiner Trap:
Link the arrangement to FORCES - it's about minimizing repulsion!
A student draws the following structure for magnesium oxide. State one error in the diagram.
Student's diagram of magnesium oxide (contains an error!):
⚠️ Can you spot the error?
⚠️ Examiner Trap:
Common errors: wrong ratio, touching spheres, no alternating pattern.
Examiner's Top Tips
- •KEYWORD ALERT: Always use "giant" when describing ionic structures - it's worth a mark!
- •FORCE SPECIFICITY: "Electrostatic forces" scores marks; "strong bonds" is too vague.
- •RATIO MATTERS: For CaF₂, mention "1:2 ratio" or "twice as many fluoride ions".
- •DRAWING RULES: Alternating pattern, regular spacing, no overlapping spheres!
- •SIZE CLUE: Anions (negative ions) are usually drawn LARGER than cations.
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