AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
Students should be familiar with the structure of sodium chloride but do…
Full specification wording
Ionic compounds: Students should be familiar with the structure of sodium chloride but do not need to know the structures of other ionic compounds.
You need to know the structure of sodium chloride in detail.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 6 of 6
Study notes
From the checked teaching notes for this specification point.
The idea
You need to know the structure of sodium chloride in detail. It is a giant ionic lattice with Na⁺ and Cl⁻ ions arranged in a regular three-dimensional pattern. Each Na⁺ ion is surrounded by six Cl⁻ ions, and each Cl⁻ ion is surrounded by six Na⁺ ions. The empirical formula is NaCl because the ratio of Na⁺ to Cl⁻ is 1:1. You should be able to describe this structure, draw or interpret diagrams of it, and explain its properties, such as its high melting point, using the lattice model. You do not need to recall the structures of other ionic compounds, such as magnesium oxide or calcium chloride, although you may be asked to apply the same principles to them if the information is provided.
What earns the marks
- Sodium chloride has a giant ionic lattice of Na⁺ and Cl⁻ ions.
- Each Na⁺ ion is surrounded by six Cl⁻ ions, and each Cl⁻ ion is surrounded by six Na⁺ ions.
- The ratio of Na⁺ to Cl⁻ ions is 1:1, giving the empirical formula NaCl.
- The strong electrostatic attractions in all directions explain the high melting point of sodium chloride.
- You are not required to recall the structures of other ionic compounds, but you may apply the same principles if given information.
Common mistakes and how to put them right
Drawing a molecule of sodium chloride with a single Na⁺ and a single Cl⁻.
Put it right by showing a giant lattice with many ions.
Stating that each ion is surrounded by four oppositely charged ions.
Put it right by stating six in the sodium chloride lattice.
Thinking you need to memorise the structures of all ionic compounds.
Put it right by focusing on sodium chloride and applying principles to others if data is provided.
Exam tips
- Learn the key features of the sodium chloride lattice: six-coordinate, 1:1 ratio, giant structure.
- When explaining properties, always link them to the strong electrostatic attractions in the lattice.
- If asked about another ionic compound, use the same reasoning as for sodium chloride but base your answer on the information given.
Try the lesson
The start of the Ionic compounds: Students should be familiar with the structure of sodium chloride but do not need to know the structures of other ionic compounds. lesson, made from checked teaching notes for this specification point.
Have a go first
Which of the following best describes the structure of solid sodium chloride?
Listen
You need to know the structure of sodium chloride in detail. It is a giant ionic lattice with Na⁺ and Cl⁻ ions arranged in a regular three-dimensional pattern. Each Na⁺ ion is surrounded by six Cl⁻ ions, and each Cl⁻ ion is surrounded by six Na⁺ ions. The empirical formula is NaCl because the ratio of Na⁺ to Cl⁻ is 1:1. You should be able to describe this structure, draw or interpret diagrams of it, and explain its properties, such as its high melting point, using the lattice model. You do not need to recall the structures of other ionic compounds, such as magnesium oxide or calcium chloride, although you may be asked to apply the same principles to them if the information is provided. A strong answer earns marks for these points. Sodium chloride has a giant ionic lattice of Na⁺ and Cl⁻ ions. Each Na⁺ ion is surrounded by six Cl⁻ ions, and each Cl⁻ ion is surrounded by six Na⁺ ions. The ratio of Na⁺ to Cl⁻ ions is 1:1, giving the empirical formula NaCl. The strong electrostatic attractions in all directions explain the high melting point of sodium chloride. A common slip: Drawing a molecule of sodium chloride with a single Na⁺ and a single Cl⁻. Instead, showing a giant lattice with many ions. Exam tip: Learn the key features of the sodium chloride lattice: six-coordinate, 1:1 ratio, giant structure.
See it
Label the diagram
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