Diamond — AQA GCSE Chemistry
Test yourself on Diamond with AQA GCSE practice questions.
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Diamond explained
Diamond is a giant covalent lattice of carbon atoms.
Read the full explanation
Each carbon atom forms four single covalent bonds to four other carbon atoms, arranged tetrahedrally. Because each bond is shared between two atoms, the ratio of atoms to bonds is 1:2 and every outer electron is localised in a bond. This rigid three-dimensional network has no separate molecules and no free electrons or ions. Consequently diamond has a very high melting point because many strong covalent bonds must be broken, it is extremely hard because the lattice resists deformation, and it does not conduct electricity because there are no delocalised electrons or ions to carry charge. For example, this explains its use in cutting tools and drill tips.
Your focus
- Describe the giant covalent lattice structure of diamond, including four covalent bonds per carbon atom.
- Explain why diamond has a very high melting point and is extremely hard.
- Explain why diamond does not conduct electricity in terms of localised electrons.
Diamond exam tips
Marking Points
- States that each carbon atom in diamond forms four covalent bonds to four other carbon atoms.
- Describes the arrangement as a giant covalent lattice or tetrahedral network with no separate molecules.
- Links the high melting point to the many strong covalent bonds that must be broken.
- Links the extreme hardness to the rigid three-dimensional network of strong covalent bonds.
- Explains that diamond does not conduct electricity because all outer electrons are localised in covalent bonds, so there are no delocalised electrons or ions.
Examiner Tips
- 💡Name the structure first, then link each property to a structural feature in a because clause.
- 💡Use the phrase many strong covalent bonds must be broken when explaining the high melting point.
- 💡State explicitly that there are no delocalised electrons or ions when explaining why diamond does not conduct electricity.
Common Mistakes
- Saying diamond is made of small molecules: correct this by describing a giant covalent lattice with no separate molecules.
- Saying diamond conducts electricity because it contains carbon: correct this by stating that all four outer electrons per carbon are localised in covalent bonds, so there are no delocalised electrons.
- Saying diamond has a high melting point because covalent bonds are weak: correct this by stating the bonds are strong and many must be broken.