What are some examples of bulk materials.
Lumps or powders
What is a nano particle
A nano particle is a structure that is 1-100nm in size. It contains a few hundred atoms
What size is one nanometre
0.000 000 001m or 1x10-9m
How do you convert from nanometres to metres using standard for
Single digit numbers = number x10-9m
Double digits=number as a decimal x 10-8m
Three digit= number as a decimal x10-7m
Why do nano particles have different properties from their bulk material? 
Nano particles have very different properties and uses from their bulk material due to their high surface area to volume ratio 
Give an example of how nano particles properties are different to their bulk material
For example, bulk gold is very unreactive however gold nano particles can be used as a catalyst in some chemical reactions 
How do you calculate the surface area of a cube
Area of one side = l x b
Surface area = area of one side x 6
Units2
How do you calculate volume
Volume = l x b x h units3
How do you show surface area to volume ration
Write the two numbers sided by side and reduce evenly until volume = 1 unit3
What happens to the surface area to volume ratio when nano particles/cubes becomes smaller by factor of 10?
When the size of a nano particle/cube has decreased by a factor of 10, the surface area of volume ratio increases by factor of 10
Why do nano particles have such a high surface are to volume ratio
Nano-particles have a very large surface area to volume ratio due to the very small size 
Why is suncream used
To protect the skin from some of the suns ultraviolet radiation to prevent sunburn 
What did sun creams used to contain?
The chemical zinc oxide
Why do sun creams no longer use the chemicals zinc oxide and what do they use instead?
The chemical Zinc oxide is a white solid that absorbs ultraviolet radiation however it’s very difficult to rub in so more often nano particles of zinc oxide are used in suncreams instead of
Benefits of using nano particles of zinc oxide in sun cream
-They give better skin coverage to the suncream
-They provide more effective protection from the suns ultraviolet rays
-They are clear and colourless which makes the suncream invisible on the skin and therefore easier to rub in
-They do not degrade on exposure to the Sun
Risks of using nano particles of zinc oxide in suncream
-there is potential cell damage in the body nano particles are so small they may be able to be breathed in or be able to penetrate cell membranes. In the body the nano particles may be more reactive or more toxic than the bulk material.
-Harmful effects on the the environment
Why are the risks of zinc oxide nano particles pretty unknown
Bulk zinc oxide was safe to use in sun creams so it is assumed that nanoparticles of zinc oxide or also safe for us to use.
However nano-particles have not been used long in suncreams so the risks are difficult to determine and with them being so small can be hard to research 🔬
