AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
In diamond, each carbon atom forms four covalent bonds with other carbon…
Full specification wording
Diamond: In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity.
Diamond is a giant covalent structure made only of carbon atoms.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 1 of 2
- 2 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Diamond is a giant covalent structure made only of carbon atoms. Each carbon atom forms four strong covalent bonds to four other carbon atoms, arranged tetrahedrally. This means every carbon atom is bonded to four neighbours, producing a rigid three-dimensional network that extends throughout the crystal. A large amount of energy is needed to break these many strong covalent bonds, so diamond has a very high melting point. The rigid network also makes diamond extremely hard, which is why it is used in cutting tools and drill bits. In diamond, all four outer electrons of each carbon atom are used in covalent bonding, so there are no delocalised electrons or free ions. As a result, diamond does not conduct electricity.
What earns the marks
- Diamond is a giant covalent structure in which each carbon atom forms four covalent bonds to other carbon atoms.
- The carbon atoms are arranged in a rigid three-dimensional network, which makes diamond very hard.
- Many strong covalent bonds must be broken to melt diamond, so it has a very high melting point.
- All outer electrons are used in covalent bonding, so there are no delocalised electrons or free ions to carry charge.
- Because there are no mobile charge carriers, diamond does not conduct electricity.
Common mistakes and how to put them right
Saying that diamond conducts electricity because it contains carbon.
Put it right: Carbon alone does not guarantee conduction, and diamond has no delocalised electrons.
Stating that diamond has a high melting point because of weak intermolecular forces.
Put it right: In a giant covalent structure, strong covalent bonds must be broken.
Describing diamond as a molecule.
Put it right: It is a giant covalent lattice, not a simple molecular substance.
Exam tips
- State the number of covalent bonds per carbon atom and link this to the giant rigid structure.
- Explain hardness and high melting point by referring to the strong covalent bonds throughout the network.
- Explain electrical non-conduction by stating that there are no delocalised electrons or free ions.
Try the lesson
The start of the Diamond: In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity. lesson, made from checked teaching notes for this specification point.
Have a go first
How many covalent bonds does each carbon atom form in diamond?
Listen
Diamond is a giant covalent structure made only of carbon atoms. Each carbon atom forms four strong covalent bonds to four other carbon atoms, arranged tetrahedrally. This means every carbon atom is bonded to four neighbours, producing a rigid three-dimensional network that extends throughout the crystal. A large amount of energy is needed to break these many strong covalent bonds, so diamond has a very high melting point. The rigid network also makes diamond extremely hard, which is why it is used in cutting tools and drill bits. In diamond, all four outer electrons of each carbon atom are used in covalent bonding, so there are no delocalised electrons or free ions. As a result, diamond does not conduct electricity. A strong answer earns marks for these points. Diamond is a giant covalent structure in which each carbon atom forms four covalent bonds to other carbon atoms. The carbon atoms are arranged in a rigid three-dimensional network, which makes diamond very hard. Many strong covalent bonds must be broken to melt diamond, so it has a very high melting point. All outer electrons are used in covalent bonding, so there are no delocalised electrons or free ions to carry charge. Exam tip: State the number of covalent bonds per carbon atom and link this to the giant rigid structure.
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Key words
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Hardness and melting point
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Electrical conductivity and mobile charge carriers
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See every definition
- Hardness and melting point
- The rigid network makes diamond very hard, and many strong covalent bonds must be broken to melt it, so it has a very high melting point.
- Electrical conductivity and mobile charge carriers
- All outer electrons are used in covalent bonding, so there are no delocalised electrons or free ions, and diamond does not conduct electricity.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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