Distinguish between the arrangement of carbon atoms at the sides and at the ends of carbon nanotubes.

Sides:

Ends:

Outline why bundles of carbon nanotubes have high tensile strength.

Discuss two concerns regarding the development of nanotechnology.

Sides:

(atoms arranged in) hexagons

and

Ends:

(atoms arranged in) pentagons (and hexagons);

strong covalent/C–C bonding (in the walls of the nanotubes) / OWTTE;

possible toxicity of small (airborne) particles;

explosive / small size/large surface area means dangerously fast reactions;

unknown health effects / immune system/allergy concerns;

uncertain impact on environment;

lack of public awareness about dangers;

increasing economic disparity between developed and developing nations;

Accept other valid concerns.

A correct definition of nanotechnology was often seen and many candidates knew the difference between the arrangement of carbon atoms at the sides and at the ends of carbon nanotubes. Reference to the presence of strong covalent bonding between the carbon atoms to explain the high tensile strength of the bundles of nanotubes was not seen in most scripts.

A correct definition of nanotechnology was often seen and many candidates knew the difference between the arrangement of carbon atoms at the sides and at the ends of carbon nanotubes. Reference to the presence of strong covalent bonding between the carbon atoms to explain the high tensile strength of the bundles of nanotubes was not seen in most scripts.

A correct definition of nanotechnology was often seen and many candidates knew the difference between the arrangement of carbon atoms at the sides and at the ends of carbon nanotubes. Reference to the presence of strong covalent bonding between the carbon atoms to explain the high tensile strength of the bundles of nanotubes was not seen in most scripts.