Nano-scale Particles (WJEC GCSE Chemistry)
Revision Note
Nano-scale Particles
Nanoparticles are between 1 and 100 nanometres in size and usually contain only a few hundred atoms
Atoms and simple molecules are around 100 times smaller than this
The research into the production and application of nanoparticles is called nanoscience
One of the most interesting features of nanoparticles is their very high surface area to volume ratio
As particles decrease in size, their surface area increases in relation to their volume
As the side of a cube decreases by a factor of 10, the surface area to volume ratio increases by a factor of 10
This is why nanoparticles may have properties different from those of the same materials in bulk
It may also mean that smaller quantities are needed to be effective than for materials with normal particle sizes
Diagram showing the size of nanoparticles relative to other objects and substances
Nanoparticles are between 1 and 100 nanometres in size
Nanoparticles of Silver
Nanoparticles of silver have antibacterial and antifungal properties
They are able to kill microorganisms such as bacteria and viruses
They do this without harming humans and other organisms
This property allows them to be used in the following applications:
Sports clothing to prevent body odour
Body odour is caused by bacteria on the surface of the skin so killing the bacteria using silver nanoparticles reduces body odour
Cleaning surgical equipment
The nanoparticles will kill the bacteria on the surface of the equipment prior to operations
In fridges as an anti-bacterial coating
Odours in a fridge are caused by bacteria found on the surfaces so the nanoparticles will kill these bacteria and prevent the odours
Nanoparticles of Titanium Dioxide
These nanoparticles are able to reflect UV light whilst also allowing visible light to pass through
This property allows them to be used in the following applications:
Transparent sunscreens
The nanoparticles block the UV light from penetrating the skin reducing the chance of sunburn and skin cancer
Due to the particles being so small, they cannot be seen on the surface of the skin
Self cleaning windows
The window is coated with titanium dioxide nanoparticles
They break down the dirt on a window surface whenever UV light from the sun shines on them
They also cause water to spread out in a thin film rather than forming droplets on the surface, cleaning the window
Photo by Christian Wiediger on Unsplash
Nanoparticles of titanium dioxide are used in self-cleaning windows
Risks of Using Nano-scale Particles
Higher Tier
Nanoparticles have widespread uses and applications that can provide an immense advance in materials technology
The use of nanoparticles in science is in its early stages so there are still a lot of unknown factors and potential risks
In particular, there is a lack of understanding of how they may affect health
E.g. Some people have expressed concern that nanoscale silver, used in deodrants, and titanium dioxide, used in sunscreens, are applied to the skin and can therefore be easily absorbed into the body
Nanoparticles are so small that they could potentially enter living cells or enter the bloodstream through our skin
Although there haven’t been any serious short term side effects, there could be long term side effects which we haven’t detected yet as they haven’t been in use long enough
Even a small amount of toxicity in a particular nanoparticle would be multiplied due to the high surface area to volume ratio
This coupled with the fact that they are not easily disposed of by the body are a cause for caution in the medical application of nanoparticles
Examiner Tips and Tricks
Silver and titanium dioxide are named in the specification as the two types of nanoparticles you need to be aware of - so make sure you learn the uses of each one!
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