Graphene and fullerenes (AQA GCSE Chemistry): Revision Notes
Graphene and fullerenes
Carbon is an amazing element that can form different structures with unique properties. Beyond diamond and graphite, carbon also exists as graphene, fullerenes, and carbon nanotubes. These newer forms of carbon have exciting applications in technology and medicine.
What is graphene?
Graphene consists of just one layer taken from graphite's structure. This single layer has the thickness of only one carbon atom, making it incredibly thin yet remarkably strong.
Graphene is literally just one atom thick - imagine peeling off a single layer from a pencil lead. Despite this incredible thinness, it's one of the strongest materials known to science.
In graphene's structure, each carbon atom connects to three neighbouring carbon atoms through strong covalent bonds. These atoms arrange themselves in a hexagonal pattern, creating a flat sheet that looks like chicken wire under a microscope.
Properties and uses of graphene
Graphene has two main properties that make it very useful:
Electrical conductivity: Graphene conducts electricity extremely well, making it perfect for electronic devices. Engineers use it to create faster, more efficient circuits and touchscreens.
Application Example: Touchscreen Technology
Modern smartphones use graphene-enhanced touchscreens because:
- Graphene's excellent conductivity allows for more responsive touch detection
- Its transparency doesn't interfere with the display
- Its flexibility enables bendable screens in future devices
Strength and lightness: Despite being only one atom thick, graphene is incredibly strong. It can be mixed with other materials to create lightweight composites that are both strong and have low density. These composites are useful in aircraft and sports equipment.
What are fullerenes?
Fullerenes are molecules made entirely of carbon atoms arranged in hollow, cage-like structures. Think of them as carbon footballs or tubes - they have empty spaces inside their structures.
The name "fullerene" comes from architect Buckminster Fuller, who designed geodesic domes with similar geometric patterns to these carbon molecules.
These molecules are built from hexagonal rings of carbon atoms, similar to graphene. However, fullerenes can also contain five-carbon and seven-carbon rings, which help create their curved, three-dimensional shapes.
Types of fullerenes
Spherical fullerenes: The most famous example is Buckminsterfullerene (also called buckyballs), with the chemical formula . This molecule contains exactly 60 carbon atoms arranged in a sphere shape, similar to a football.
Structural Example: Buckminsterfullerene ()
Imagine a football (soccer ball) made of carbon atoms:
- 60 carbon atoms form the structure
- 12 pentagonal faces (5-sided) and 20 hexagonal faces (6-sided)
- Each carbon atom connects to exactly 3 other carbon atoms
- The result is a hollow sphere about 1 nanometer in diameter
Carbon nanotubes: These are cylindrical fullerenes that are extremely long compared to their width. Imagine rolling up a sheet of graphene into a tiny tube - that's essentially what a carbon nanotube looks like.
Properties of carbon nanotubes
Carbon nanotubes have several remarkable properties:
- High tensile strength: They are incredibly strong and difficult to break when pulled
- Electrical conductivity: They conduct electricity very well
- Heat conductivity: They also conduct heat efficiently
Carbon nanotubes can be up to 100 times stronger than steel while being only 1/6th the weight. This extraordinary strength-to-weight ratio makes them revolutionary for engineering applications.
Uses of fullerenes and carbon nanotubes
The unique properties of these carbon structures lead to many practical applications:
Medical applications: Fullerenes can carry drugs inside the body, acting like tiny delivery vehicles to transport medicine to specific areas where it's needed.
Lubricants: Their smooth, rounded structure makes fullerenes excellent lubricants, reducing friction between moving parts in machinery.
Fullerenes work as lubricants because their spherical shape allows them to roll between surfaces rather than slide, significantly reducing wear and friction.
Catalysts: Fullerenes provide large surface areas that can speed up chemical reactions, making them useful as catalysts.
Technology applications: Carbon nanotubes are used in nanotechnology to create incredibly small devices and components.
Electronics: Their excellent conductivity makes carbon nanotubes valuable for electronic circuits and components.
New materials: Engineers use carbon nanotubes to strengthen materials, such as reinforcing the frames of tennis rackets to make them lighter yet stronger.
Key Points to Remember:
- Graphene is a single layer of carbon atoms arranged in hexagons, only one atom thick
- Graphene conducts electricity well and is used in electronics and strong, lightweight composites
- Fullerenes are hollow carbon structures that can be spherical (like buckyballs) or cylindrical (like carbon nanotubes)
- Carbon nanotubes have high strength and conduct electricity and heat well, making them useful in technology and materials
- These carbon structures have many applications including medicine, electronics, lubricants, and strengthening materials