Nanoparticles of a material can have different properties to the same material in bulk. Explain why nanoparticles have different properties to the same material in bulk.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Silver is used as an antibacterial agent. Silver nanoparticles are more effective as an antibacterial agent than the same mass of bulk silver.
Model answer (4 marks)
Nanoparticles are much smaller than bulk materials – their diameters are 1–100 nm.
Because they are so small they have a much larger surface area to volume ratio than bulk material.
A greater proportion of atoms are exposed on the surface compared with bulk material.
This higher surface exposure allows nanoparticles to interact or react more effectively with their surroundings, giving them different or enhanced properties.
Because they are so small they have a much larger surface area to volume ratio than bulk material.
A greater proportion of atoms are exposed on the surface compared with bulk material.
This higher surface exposure allows nanoparticles to interact or react more effectively with their surroundings, giving them different or enhanced properties.
Examiner tips
- Use the exact terms: ‘surface area to volume ratio’, ‘exposed atoms’, ‘react more effectively’.
- Show the logical chain: size → ratio → surface atoms → property change.
- Keep each point brief – 1 mark each.
Common mistakes
- Confusing ‘size’ with ‘surface area’; writing only ‘small size’ without ratio.
- Using vague phrases like ‘different properties’ without linking to surface area.
- Including irrelevant details such as synthesis methods.
Mark scheme (4 marks)
- Nanoparticles are much smaller than bulk materials / nanoparticles have diameters of 1–100 nm
- Nanoparticles have a much larger surface area to volume ratio than bulk material
- A greater proportion of atoms are exposed / on the surface (compared to bulk material)
- This means nanoparticles can interact / react more effectively with their surroundings, leading to different / enhanced properties
Key terms in this question
Related
- All AQA GCSE Chemistry (8462) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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