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Nanoparticles: sizes, risks and uses explained

Bonding, structure and the properties of matter • Bulk and surface properties

Key concepts

What you'll likely be quizzed about

  • The nanometre (nm) is one billionth of a metre (1 × 10−9 m).
  • Atoms generally have diameters around 0.1–0.3 nm.
  • Simple molecules are approximately 0.3–1 nm in size.
  • Nanoparticles fall within the size range of 1–100 nm, bridging the gap between single molecules and larger particles that are visible.
  • The nanometre creates a measurable distinction between molecular-scale matter and nanoscale matter.
  • Factors affecting behavior include particle shape and aggregation; particles smaller than 1 nm behave like large molecules, while those larger than 100 nm show bulk-like characteristics.

Flashcards

Test your knowledge with interactive flashcards

What is the precautionary principle in nanoparticle use?

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The precautionary principle favours caution and risk minimisation when evidence about harm is incomplete.

Key notes

Important points to keep in mind

Nanoparticles measure between 1 nm and 100 nm; atoms and simple molecules are smaller.

High surface-area-to-volume ratio increases reactivity and alters physical properties.

Toxicity depends on size, chemistry, surface coating, dose, and exposure route.

Aggregation and surface treatments reduce accessible surface area and change particle behavior.

Exposure routes include inhalation, ingestion, and skin contact; each route alters risk.

Evaluation requires evidence of benefit, exposure assessment, lifecycle analysis, and alternatives.

Incomplete long-term data justifies cautious decision-making and preference for safer substitutes.

Mitigation controls include coatings, containment, engineering controls, and personal protective equipment.

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