C3 - Structure and Bonding Flashcards
What are nano particles?
Structures that are 1 - 100nm in size, of the order of a few hundred atoms
What are Fine Particles
PM2.5 - diameters between 100 and 2500nm (1x10⁻⁷m and 2.5x10⁻⁶m)
What are Coarse Particles
PM10 - often referred to as dust (diameters between 1x10⁻⁵ and 2.5x10⁻⁶m)
As the side of a cube decreases by a factor of 10…
…the surface area to volume ratio increases by a factor of 10
Why might nanoparticles have different properties to those for the same material in bulk?
Due to their very high surface area to volume ratio
What is another effect of nanoparticles’ high SA:vol ratio?
Smaller quantities are needed to be effective than for materials with normal particles
How can nanoparticles be used?
- Medicine
- Electronics
- Cosmetics and suncreams
- As deodorants
- As catalysts
How are nanoparticles used in cosmetics and suncreams?
- Cosmetics - in face creams so that the creams are absorbed deeper into the skin
- Suncreams - titanium oxide and zinc oxide coated with silica are more effective at blocking the Sun’s rays than conventional UV absorbers
How are nanoparticles used in medicine?
- Nanocages of gold warmed up by lasers to damage tumour
- Gold nanocages carry drugs directly to cancer tumours without damaging surrounding cells
- Silver nanoparticles are used to inhibit the growth of microorganisms, for example in fridges and antimicrobial coatings
What are the possible risks of nanoparticles?
- Effective as catalysts, but if a spark is made near a large quantity of catalyst there could be an explosion
- Potential risk of nanoparticles in the atmosphere; dangerous to our lungs and enter the bloodstream, with unpredictable effects on cells
- Nanoparticles entering the environment e.g. affecting aquatic organisms
- There is little research on the long term effects of nanoparticles
