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18 Carbon nanotubes are a new material - OCR Gateway - GCSE Chemistry: Combined Science - Question 18 - 2018 - Paper 1
Question 18
18 Carbon nanotubes are a new material. The diagrams show how a graphene sheet can form a nanotube. (a) Nanotubes are more than 100 times stronger than iron. Explai... show full transcript
Worked Solution & Example Answer:18 Carbon nanotubes are a new material - OCR Gateway - GCSE Chemistry: Combined Science - Question 18 - 2018 - Paper 1
Step 1
Explain why nanotubes are so strong. Use ideas about bonding.
Answer
Nanotubes possess exceptional strength due to their unique structure and bonding. The carbon atoms in nanotubes are arranged in a hexagonal lattice, similar to graphene, where each carbon atom is covalently bonded to three neighboring carbon atoms. This strong covalent bonding creates a stable, rigid structure, which is resistant to deformation.
Moreover, the presence of numerous carbon-carbon bonds makes it extremely difficult to break these connections, contributing to the material's strength. Additionally, the tubular shape of nanotubes allows for the distribution of stress along its length, enabling them to withstand significant tensile forces without fracture.
Step 2
Explain why carbon nanotubes conduct electricity.
Answer
Carbon nanotubes conduct electricity due to the presence of delocalized electrons that can move freely along the length of the tube. In the arrangement of carbon atoms, one valence electron from each carbon forms a strong covalent bond with neighboring carbon atoms, while the remaining electron contributes to a 'pi-bonding' network.
These delocalized electrons are not bound to any specific atom, allowing them to move easily throughout the nanotube structure. This movement of electrons is essential for electrical conductivity, making carbon nanotubes excellent conductors of electricity.