Chemistry · Bonding, Structure and Properties of Matter
Nanoparticles
Spec 5.2.3.3📗 Foundation
Interactive · work the surface-area-to-volume calculation
Theory · read, then commit
Nanoparticles are tiny particles 1–100 nm across (1 nm = 1×10⁻⁹ m), containing a few hundred to a few thousand atoms. At this scale a material can behave very differently from its bulk form.
🟡Bulk gold
ColourYellow
ReactivityLow — unreactive with most chemicals
Melting point1064 °C
🔴Gold nanoparticles
ColourRed / purple
ReactivityMuch higher
Melting pointMuch lower
Same gold atoms — but a huge surface-area-to-volume ratio means far more atoms sit on the surface, so reactivity shoots up.
Checkpoint · quick check
Describe what happens to a particle's surface-area-to-volume ratio as the particle gets smaller.
⚠️ Common Mistake
Students often think that a nanoparticle of gold must be a different substance from ordinary gold because its colour and reactivity are so different. It is the same substance — the same gold atoms. What changes is the scale: nanoparticles have a far larger surface-area-to-volume ratio, so a much greater fraction of their atoms sit on the surface, which changes their properties.
▦Graphene
A single layer of graphite, one atom thick — extremely strong, very light, and conducts electricity.
⚽Buckminsterfullerene (C₆₀)
60 carbon atoms in a hollow sphere ('buckyball') — can cage molecules; used in drug delivery and lubricants.
🛢️Carbon nanotube
A rolled-up graphene sheet forming a hollow tube — very strong along its length and conducts electricity.
✅Uses of nanoparticles
Sunscreen: TiO₂ nanoparticles are transparent but still block UV.
Antibacterial: silver nanoparticles — high surface area → very reactive against bacteria.
Catalysis: a high surface area makes them very effective catalysts.
Drug delivery: they can carry medicine directly to target cells.
Checkpoint · quick check
Silver nanoparticles are added to wound dressings. Suggest why their small size makes them suitable for this use.
⚠️ Risks — why more research is needed
Nanoparticles are so small they may pass through cell membranes, be breathed deep into the lungs, and persist in the environment and food chains. Their long-term health and environmental effects are not yet fully understood.
Retrieval · Match the Carbon Nanostructure
Test yourself · 8 questions, exam order
⭐Examiner Tip
When asked why nanoparticles behave differently from the bulk material, the marks are for the surface-area-to-volume ratio — say a much greater fraction of the atoms sit on the surface. Never write that it is a "different substance": it is the same atoms at a smaller scale.
0 of 8 answered
Warm-up · 2 questions
Explain why nanoparticles have different properties from the same material in bulk (large-scale) form.
Suggest why nanoparticles may pose a greater health risk than the same material in larger particle form.
Exam standard · 4 questions
Explain why nanoparticles make very effective catalysts.
Titanium dioxide nanoparticles are used in sunscreen. Suggest why the nanoparticle form is used instead of bulk titanium dioxide.
State the range of sizes (in nanometres) that defines a nanoparticle.
Identify a use of nanoparticles.
Stretch · 2 questions
Name the carbon nanostructure that is a single layer of graphite, one atom thick.
Identify one possible risk of using nanoparticles.
Key note · cover it, say it, check it
Revision card · 6 stepsNanoparticles
01Nanoparticles: 1–100 nm.
02Huge surface area to volume ratio → different properties, higher reactivity.
03Graphene: single layer of graphite, strong, conducts.
04Fullerenes (C₆₀): hollow carbon spheres, drug delivery.
05Nanotubes: rolled graphene, strong conductors.
06Risks: may penetrate cells, unknown long-term effects.
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