2.3.5

Allotropes of Carbon

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Diamond

Diamond is an allotrope (form) of carbon. Diamond has the following properties:

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Covalent bonds

  • Each carbon atom in diamond is bonded to four other carbon atoms by strong covalent bonds.
    • This creates a giant covalent structure.
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Hard

  • There are lots of strong covalent bonds in diamond. This makes it very hard.
    • Because diamond is hard, it is used as a cutting tool to cut other materials.
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Does NOT conduct electricity

  • Diamond does NOT conduct electricity because there are no delocalised electrons in the diamond structure.
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High melting point

  • A lot of energy is needed to break strong covalent bonds.
  • Diamond has lots of strong covalent bonds. This means that it has a high melting point.
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Thermal conductivity

  • Diamond has a very rigid structure.
    • This means that vibrations can easily carry heat throughout the structure.
    • Diamond is an excellent thermal conductor.

Graphite

Graphite is an allotrope (form) of carbon. Graphite has the following properties:

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Covalent bonds

  • Each carbon atom in graphite is bonded to 3 other carbon atoms by strong covalent bonds.
    • This creates a giant covalent structure.
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Strong covalent bonds

  • Due to the strong covalent bonds within the sheets, graphite:
    • Has a high melting point.
    • Is insoluble in solvents.
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Soft

  • The carbon atoms form layers of hexagonal (6-sided) rings, with each layer held together by weak intermolecular forces.
  • The layers can slide over one another easily, so graphite is very soft.
    • This makes it useful as a lubricant and as pencil ‘lead’.
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Conducts electricity

  • Each carbon atom forms 3 covalent bonds.
  • 1 electron from every carbon atom in graphite is delocalised.
  • This electron can move freely, so graphite can conduct electricity.

Jump to other topics

1Structure - Models of the Particulate of Matter

2Structure - Models of Bonding & Structure

3Structure - Classification of Matter

3.1The Periodic Table: Classification of Elements

3.2Periodic Trends

3.3Group 1 Alkali Metals

3.4Halogens

3.5Noble gases, group 18

3.6Functional Groups: Classification of Organic

3.7Functional Group Chemistry

3.8Alkanes

3.9Alcohols

3.10Halogenoalkanes

4Reactivity - What Drives Chemical Reaction?

5Reactivity - How Much, How Fast & How Far?

6Reactivity - The Mechanisms of Chemical Change

7Measurement, Data Processing & Analysis

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