Graphene is a single layer of graphite and has properties that make it…

The idea

Graphene is one layer of graphite, just one atom thick, in which carbon atoms are arranged in a hexagonal lattice. Each carbon atom bonds covalently to three others, leaving one delocalised electron per atom. Because the layer is only one atom thick, graphene is extremely thin, has a very large surface area for its mass, and is strong yet flexible. The delocalised electrons make it an excellent electrical conductor, which is why it is used in electronics, for example in fast transistors, touchscreens and conductive inks. Its strength, low mass and large surface area make it useful in composites, where it is added to materials such as plastics to reinforce them or to add conductivity. Graphene is not a molecule with a fixed small number of atoms; it is a single extended layer, so its properties come from its giant covalent sheet structure.

What earns the marks

• Graphene is a single layer of graphite, one atom thick, with carbon atoms in a hexagonal arrangement.
• Each carbon atom forms three covalent bonds, leaving delocalised electrons that allow graphene to conduct electricity.
• The one-atom-thick sheet gives graphene a very large surface area relative to its mass.
• Graphene is strong and flexible, which helps it reinforce composite materials.
• Its high electrical conductivity makes graphene suitable for electronic devices and conductive components.
• Graphene is an extended single layer rather than a small molecule with a fixed formula.

Common mistakes and how to put them right

• Describing graphene as many layers of graphite.

  Put it right by stating that graphene is a single layer only.

• Saying graphene conducts because it contains metal atoms.

  Put it right by explaining that conduction comes from delocalised electrons in the carbon lattice.

• Treating graphene as a small fullerene molecule.

  Put it right by distinguishing the extended single layer of graphene from hollow molecular fullerenes.

Exam tips

• Name a specific electronic or composite use and link it to a named property, such as conductivity for electronics or strength for composites.
• Use the phrase single layer of graphite to show the structural relationship clearly.
• Avoid vague words such as strong on their own; add a consequence, such as reinforcing a composite without adding much mass.