AQA GCSE Combined Science (8464), Higher tier · Chemistry › Bonding, structure, and the properties of matter › Structure and bonding of carbon
Practise Graphene and fullerenes. 12 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Graphene (a single layer of graphite) and fullerenes (hollow carbon molecules such as buckminsterfullerene and carbon nanotubes). You need to recognise them from diagrams and descriptions, explain the properties of graphene, and give uses of fullerenes and nanotubes.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
Describe graphene as one layer of graphiteGraphene is a single layer of carbon atoms in hexagonal rings, one atom thick.
4
Describe fullerenes as hollow carbon moleculesThey are based on hexagonal rings of carbon atoms, sometimes with rings of five or seven atoms.
4
Name buckminsterfullerene and give its formulaThe first fullerene discovered: C60, a hollow, spherical molecule.
5
Give uses of fullerenes and nanotubesFullerenes: drug delivery, lubricants, catalysts; nanotubes: nanotechnology, electronics and strengthening materials.
6
Explain the properties of grapheneStrong covalent bonds make it very strong; delocalised electrons let it conduct electricity.
7
Describe carbon nanotubes and their propertiesCylindrical fullerenes with a very high length to diameter ratio; very strong and conduct electricity.
8
Explain why C60 has a lower melting pointC60 is molecular, so melting overcomes weak intermolecular forces, not covalent bonds.
Notes
Graphene
Graphene is a single layer of graphite: carbon atoms in hexagonal rings, just one atom thick.
Each carbon atom forms three strong covalent bonds, and one electron from each atom is delocalised.
It is very strong, because the atoms are held together by strong covalent bonds across the whole layer.
It conducts electricity, because the delocalised electrons can move across the layer.
These properties, and the fact that it is so thin and light, make graphene useful in electronics and in composites (adding graphene to another material can make it much stronger).
Fullerenes
Fullerenes are molecules of carbon atoms with hollow shapes.
Their structure is based on hexagonal rings of carbon atoms, but they may also contain rings of five or seven carbon atoms.
The first fullerene to be discovered was buckminsterfullerene, C60. Its molecules are spherical, made of rings of five and six carbon atoms, like the pattern on a football.
Uses of fullerenes: carrying drugs into the body (the hollow cage can hold a drug molecule), lubricants, and catalysts (they have a large surface area).
C60 is made of separate molecules with weak intermolecular forces between them, so it has a much lower melting point than diamond or graphite. grade 8+
Carbon nanotubes
Carbon nanotubes are cylindrical fullerenes: tubes of carbon atoms with a very high length to diameter ratio (very long compared with their width).
They are very strong (high tensile strength) because of their strong covalent bonds, and they conduct electricity because they have delocalised electrons.
Their properties make them useful in nanotechnology, electronics and materials, e.g. reinforcing the frames of tennis rackets.
Cheatsheet
Graphene = a single layer of graphite (one atom thick)
Fullerenes = hollow molecules of carbon; hexagonal rings, sometimes rings of 5 or 7 atoms
Buckminsterfullerene: C60, spherical, the first fullerene discovered
Carbon nanotubes = cylindrical fullerenes with a very high length to diameter ratio
Nanotubes: very strong, conduct → nanotechnology, electronics, materials
Fullerene uses: drug delivery, lubricants, catalysts
C60 is molecular: weak intermolecular forces → much lower melting point than graphite grade 8+
How to answer each type of question
Recognise and describe fullerenes
1 to 3 marks4
A closed, hollow cage is a fullerene such as C60; a long hollow tube is a nanotube; a flat single sheet of hexagons is graphene.
Learn the key facts: C60, spherical, rings of five and six (fullerenes can also have rings of seven).
Example. (a) Give the formula of buckminsterfullerene. (b) Describe the shape of a molecule of buckminsterfullerene. (c) Fullerenes contain rings of six carbon atoms. Give one other size of ring that fullerenes can contain.
Show the model answer
(a) C60 (1) (b) A hollow sphere / ball (1) (c) Five (or seven) carbon atoms (1)
Other fullerenes: drug delivery, lubricants, catalysts.
Give one clear use per mark.
Example. Give one use of carbon nanotubes and one use of other fullerenes.
Show the model answer
Nanotubes, any one from: reinforcing materials such as tennis rackets; electronics; nanotechnology (1). Fullerenes, any one from: delivering drugs in the body; lubricants; catalysts (1).
Explain the properties of graphene
3 to 4 marks6
Describe the structure: a single layer of carbon atoms, each bonded to three others.
Strength: strong covalent bonds.
Conductivity: one delocalised electron per carbon atom, free to move.
Example. Graphene is being developed for flexible touch screens. It is very strong and conducts electricity. Explain these two properties in terms of its structure and bonding.
Show the model answer
Graphene is a single layer of carbon atoms, each bonded to three others (1). It is strong because the atoms are joined by strong covalent bonds (1). It conducts because one electron from each carbon atom is delocalised (1), so these electrons can move across the layer and carry charge (1).
Explain why C60 has a lower melting point than graphite
4 marks8
Say C60 is made of separate molecules.
Weak intermolecular forces between them need little energy to overcome.
Graphite is a giant covalent structure: many strong covalent bonds must be broken, needing much more energy.
Example. Buckminsterfullerene has a much lower melting point than graphite. Explain why.
Show the model answer
Buckminsterfullerene is made of separate C60 molecules (1) with weak intermolecular forces between them, which need little energy to overcome (1). Graphite has a giant covalent structure (1), so many strong covalent bonds must be broken to melt it, which needs much more energy (1).
Shortcuts and memory tricks
Graphene = graphite with only one layer. Same bonding (3 bonds + 1 delocalised electron per atom), so it is strong and conducts.
C60: 60 carbon atoms shaped like a football. Buckyball = sphere; nanotube = cylinder.
Nanotube uses: tiny tech (nanotechnology), electronics and tough materials.
Where marks are lost
Calling fullerenes giant covalent structures. They are molecules (hollow cages or tubes).
Saying graphene conducts because it is a metal or because it has free ions.
Saying fullerenes contain only hexagonal rings: they can also contain rings of five or seven carbon atoms.
Mixing up the shapes: buckminsterfullerene is a sphere; nanotubes are cylinders.
Forgetting that graphene is only one atom thick.
Exam technique
To explain a property of graphene, use the same ideas as for graphite: covalent bonds for strength, delocalised electrons for conductivity.
In 'give a use' questions, one clear use per mark is enough; extra wrong answers can cancel out a right one.
Read diagrams carefully: a closed hollow cage is a fullerene, a long tube is a nanotube, and a flat single sheet of hexagons is graphene.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Graphene and fullerenes are forms of carbon. Describe the shape of a Buckminsterfullerene molecule.
a hollow sphere (ball)
Fullerenes are molecules of carbon atoms with hollow shapes. Give two uses of fullerenes.
e.g. delivering drugs into the body; lubricants
Carbon nanotubes are cylindrical fullerenes. A carbon nanotube has a diameter of 1.5 nm and a length of 0.30 mm. 1 mm = 1 × 106 nm Give the length of the nanotube in nanometres.
3.0 × 105 nm
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Graphene and fullerenes are forms of carbon.
(a) What is graphene? Tick (✓) one box.[1]
A single layer of graphite
A form of diamond
A polymer of carbon and hydrogen
A compound of carbon and oxygen
(b) What is the molecular formula of Buckminsterfullerene? Tick (✓) one box.[1]
C6
C12
C60
C600
(c) Describe the shape of a Buckminsterfullerene molecule.[1]
(d) Give one use of carbon nanotubes.[1]
Show the answer and mark scheme
(a)Answer: A single layer of graphite
(b)Answer: C60
(c)Answer: a hollow sphere (ball)
(hollow) sphere / spherical / ball
(d)Answer: e.g. reinforcing materials such as tennis rackets
Graphene is a single layer of graphite. It is only one atom thick.
(a) Graphene is useful in electronics. Explain why, in terms of its structure and bonding.[2]
(b) Graphene is added to other materials to make strong composites. Explain why graphene is very strong.[2]
(c) Graphite is soft and slippery, but graphene is not. Suggest why.[2]
Show the answer and mark scheme
(a)Answer: Each carbon atom forms three covalent bonds, so one electron from each atom is delocalised. The delocalised electrons can move through the layer, so graphene conducts electricity.
each carbon atom forms three covalent bonds, so one electron from each carbon atom is delocalised
the delocalised electrons can move through the layer, so graphene conducts electricity
(b)Answer: Each carbon atom is joined to three others by strong covalent bonds in a continuous hexagonal network, so a lot of force is needed to break it.
each carbon atom is joined to three others by strong covalent bonds
in a continuous / giant hexagonal network (so many bonds would have to break)
(c)Answer: In graphite the layers are held together only by weak forces, so they slide over each other. Graphene is a single layer, so there are no layers to slide.
in graphite, the layers are held together only by weak forces / there are no covalent bonds between the layers, so the layers slide over each other
graphene is a single layer, so there are no layers to slide over each other
Question 3Hard7 marks
Buckminsterfullerene, C60, is a molecule made of 60 carbon atoms. Each carbon atom is bonded to three other carbon atoms. Solid C60 turns into a gas at a much lower temperature than diamond or graphite.
(a) Explain why solid C60 turns into a gas at a much lower temperature than diamond.[3]
(b) Solid C60 is soft. Suggest why C60 can be used as a lubricant.[1]
(c) Graphite conducts electricity well, but solid C60 is a poor conductor, even though each carbon atom forms three bonds in both substances. Suggest why.[2]
(d) Suggest why fullerene molecules such as C60 can be used to deliver drugs into the body.[1]
Show the answer and mark scheme
(a)Answer: C60 is made of separate molecules, so only weak intermolecular forces are overcome; in diamond many strong covalent bonds must be broken.
C60 is made of (separate) molecules
only the weak intermolecular forces between molecules are overcome (the covalent bonds do not break)
in diamond many strong covalent bonds must be broken, which needs much more energy
(b)Answer: The spherical molecules can roll or slide over each other because the forces between them are weak.
the (spherical) molecules can roll / slide over each other (weak forces between molecules)
(c)Answer: In C60 the delocalised electrons are confined to each molecule; they cannot move from one molecule to the next, so charge cannot flow through the solid.
in C60 the delocalised electrons stay within each molecule
they cannot move from one molecule to another (so charge cannot flow through the solid)
(d)Answer: Drug molecules can be carried inside the hollow cage.
drug molecules can be carried inside the hollow molecule / cage