AQA · GCSE · Combined Science
Course version: 8464 · 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.
Sodium chloride is the ionic compound whose structure you must know in detail.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 6 of 6
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Sodium chloride is the ionic compound whose structure you must know in detail. It forms a giant ionic lattice in which Na⁺ and Cl⁻ ions are arranged in a regular repeating pattern. Each Na⁺ ion is surrounded by six Cl⁻ ions, and each Cl⁻ ion is surrounded by six Na⁺ ions, giving 6:6 coordination. The ions are held together by strong electrostatic forces of attraction between oppositely charged ions, acting in all directions. This explains the high melting point of sodium chloride, because a large amount of energy is needed to overcome these forces. The regular arrangement also means the ratio of Na⁺ to Cl⁻ ions is 1:1, so the empirical formula is NaCl. You do not need to recall the detailed structures of other ionic compounds such as magnesium oxide or calcium chloride; you only need to apply the general ideas of ionic bonding to them.
What earns the marks
- Describe sodium chloride as a giant ionic lattice of alternating Na⁺ and Cl⁻ ions.
- State that each ion is surrounded by six ions of opposite charge, giving 6:6 coordination.
- Explain that strong electrostatic forces of attraction act between oppositely charged ions in all directions.
- Link the strong forces to the high melting point of sodium chloride.
- State that the ratio of Na⁺ to Cl⁻ ions is 1:1, giving the formula NaCl.
Common mistakes and how to put them right
Describing sodium chloride as simple molecules rather than a giant ionic lattice.
Put it right by referring to a regular arrangement of ions held by electrostatic attraction.
Saying each ion is surrounded by four ions of opposite charge.
Put it right by stating six, as in the 6:6 coordination of sodium chloride.
Claiming that the ions are held by covalent bonds.
Put it right by explaining that the bonding is ionic, with electrostatic attraction between oppositely charged ions.
Exam tips
- Use the terms giant ionic lattice, electrostatic attraction and 6:6 coordination when describing sodium chloride.
- When explaining a property such as melting point, always link it back to the strength of the electrostatic forces and the energy needed to overcome them.
- If asked about another ionic compound, apply the same general principles rather than trying to recall a specific structure you have not been taught.
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
Sodium chloride is an ionic compound. Which description best represents the arrangement of ions in solid sodium chloride?
Listen
Sodium chloride is the ionic compound whose structure you must know in detail. It forms a giant ionic lattice in which Na⁺ and Cl⁻ ions are arranged in a regular repeating pattern. Each Na⁺ ion is surrounded by six Cl⁻ ions, and each Cl⁻ ion is surrounded by six Na⁺ ions, giving 6:6 coordination. The ions are held together by strong electrostatic forces of attraction between oppositely charged ions, acting in all directions. This explains the high melting point of sodium chloride, because a large amount of energy is needed to overcome these forces. The regular arrangement also means the ratio of Na⁺ to Cl⁻ ions is 1:1, so the empirical formula is NaCl. You do not need to recall the detailed structures of other ionic compounds such as magnesium oxide or calcium chloride; you only need to apply the general ideas of ionic bonding to them. A strong answer earns marks for these points. Describe sodium chloride as a giant ionic lattice of alternating Na⁺ and Cl⁻ ions. State that each ion is surrounded by six ions of opposite charge, giving 6:6 coordination. Explain that strong electrostatic forces of attraction act between oppositely charged ions in all directions. Link the strong forces to the high melting point of sodium chloride. A common slip: Describing sodium chloride as simple molecules rather than a giant ionic lattice. Instead, referring to a regular arrangement of ions held by electrostatic attraction. Exam tip: Use the terms giant ionic lattice, electrostatic attraction and 6:6 coordination when describing sodium chloride.
See it
Key words
Say what each word means before you turn the card.
Giant ionic lattice structure
Try answering aloud or in your head before turning the card.
Electrostatic forces of attraction
Try answering aloud or in your head before turning the card.
Structure and properties of ionic compounds
Try answering aloud or in your head before turning the card.
Limits of required knowledge
Try answering aloud or in your head before turning the card.
See every definition
- Giant ionic lattice structure
- A regular repeating pattern in which Na⁺ and Cl⁻ ions are arranged, with each ion surrounded by six ions of opposite charge.
- Electrostatic forces of attraction
- Strong forces acting in all directions between oppositely charged ions, holding them together and needing a large amount of energy to overcome.
- Structure and properties of ionic compounds
- The regular arrangement of ions and the strong forces between them explain the high melting point of sodium chloride.
- Limits of required knowledge
- Detailed structures of other ionic compounds such as magnesium oxide or calcium chloride need not be recalled; only the general ideas of ionic bonding are applied to them.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Ionic compounds: Students should be familiar with the structure of sodium chloride but do not need to know the structures of other ionic compounds.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge