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Nanoparticles

In this activity, students will learn what nanoparticles are, how they behave and why they have the unusual properties they have.

'Nanoparticles' worksheet

Key stage:  KS 4

GCSE Subjects:   Chemistry: Single Subject, Chemistry: Combined Science

GCSE Boards:   OCR 21st Century

Curriculum topic:   Material Choices

Curriculum subtopic:   Why Are Nanoparticles So Useful?

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

Nanoparticles and nanotechnology are in the news a lot. Some people think that nanoparticles will be useful, others think they will be dangerous. What's it all about?

"Nano" is one of the prefixes in the SI system of measurement; it means "1 billionth" or "10-9". A nanoparticle is a particle whose size is between about 1 and 100 nanometres. That means that a nanoparticle will have a few hundred atoms at most. Nanotechnology is technology which uses nanoparticles to make useful things happen.

Why are nanoparticles different?

The top picture here shows "normal" carbon; carbon atoms arranged in a giant covalent structure to make diamond. The bottom picture shows a carbon nanotube, which was one of the first nanoparticles discovered. Notice that all the atoms in the nanotube are at the surface of the shape. They are all available for a chemical reaction. In the diamond structure, most of the atoms are tucked away inside the structure, where they cannot react. The pattern of bonding is also different at the surface compared with inside the particle.

We can do the same sort of thing with other substances. By cutting them into smaller and smaller pieces, an increasing fraction of the atoms will be at the surface of the material. This means we can make nanoparticles of virtually any substance.

How are nanoparticles useful?

Because nanoparticles have lots of atoms at the surface of the particle, nanoparticles have different properties to the same chemicals in different particles. Here are some examples;

  1. Many nanoparticles are very reactive, so they act as excellent catalysts. In a catalyst, the surface is the relevant part of the material, so it is helpful to have a material which is nothing but surface.
  2. Some nanoparticles work well as antibacterials. Silver nanoparticles stop bacteria growing, which is useful in surgical dressings, like bandages. Adding silver nanoparticles to clothes stops bacteria growing on sweat, so the nanoparticles act as a deodorant.
  3. Some nanoparticles- for example carbon nanotubes- are able to conduct electricity.
  4. Nanoparticles of titanium dioxide are added to sunscreen. Larger particles of TiO2 are also able to do this, but they leave more marks on skin.

Another clever aspect of using nanoparticles is that their smallness means that we don't need much raw material to make lots of nanoparticles. This means that it doesn't matter if the raw materials are expensive, like gold or platinum; we won't need much!

Are nanoparticles safe for us to use?

We can't be sure whether the use of nanoparticles are safe. We know what their properties are like, but we have only used nanoparticles for a few years. We won't know for sure what their long-term effects on people are for a long time. The main risk seems to be if people breathe nanoparticles in; if nanoparticles get trapped in the lungs, they may be harmful. But at the moment, we're not sure. However, many of the uses of nanoparticles won't allow them to be breathed in, which should make their use safer.

There's a lot we still don't know about nanoparticles. We know the general things they can do, but not all the possibilities. We also need to be more sure about their long-term safety. There's lots for future scientists to still find out!

What is a nanometre?

A thousandth of a metre

A millionth of a metre

A billionth of a metre

Match these particle sizes with the number of atoms in them.

Column A

Column B

Molecule
about 1 to 10
Nanoparticle
many billions
Grain (like a grain of sand)
about 100

Imagine a block of a material. Now imagine cutting that block into more, but smaller pieces. What happens to the total surface area as you do this?

increases

stays constant

decreases

Nanoparticles are often able to speed up chemical reactions. What is the name of materials which speed up chemical reactions?

Which nanoparticles are useful as deodorants, and how does this work?

Why are TiO2 nanoparticles better than larger grains of TiO2 in sunscreen?

Only nanoparticles absorb sunlight

Nanoparticles are less toxic than large grains

Nanoparticles are cleaner than larger grains

Which of these statements best describes the safety of nanoparticles?

We know that nanoparticles are safe to use

We know that nanoparticles are definitely dangerous

Nanoparticles seem to be safe, but we can't be sure

Why do nanoparticles behave differently to larger particles of the same materials?

Nanoparticles have surfaces, bulk materials do not

Nanoparticles have much more surface area than bulk materials

Nanoparticles have less friction than bulk materials

Which organ is most likely to be at risk from the effects of nanoparticles?

eyes

lungs

skin

What is the name of this structure?

  • Question 1

What is a nanometre?

CORRECT ANSWER
A billionth of a metre
EDDIE SAYS
"Nano" means billionth, also written as 0.000 000 001 or 10-9. These particles are very very small.
  • Question 2

Match these particle sizes with the number of atoms in them.

CORRECT ANSWER

Column A

Column B

Molecule
about 1 to 10
Nanoparticle
about 100
Grain (like a grain of sand)
many billions
EDDIE SAYS
Even a small grain (like salt or sand) will have many billions of atoms. Most molecules are only a very few atoms. Nanoparticles are bigger than molecules, but much smaller than sand grains.
  • Question 3

Imagine a block of a material. Now imagine cutting that block into more, but smaller pieces. What happens to the total surface area as you do this?

CORRECT ANSWER
increases
EDDIE SAYS
Each cut creates more surface, but doesn't change the total volume of the material. That means that the surface area:volume ratio increases- remember that smaller gains lead to more surface area, and faster chemical reactions.
  • Question 4

Nanoparticles are often able to speed up chemical reactions. What is the name of materials which speed up chemical reactions?

CORRECT ANSWER
catalyst
catalysts
EDDIE SAYS
Catalysts are relevant when thinking about reaction rates, because they make reactions go faster. Nanoparticles are often very good catalysts.
  • Question 5

Which nanoparticles are useful as deodorants, and how does this work?

CORRECT ANSWER
EDDIE SAYS
Sweat smells when bacteria digest it, so killing the bacteria prevents nasty armpit smells.
  • Question 6

Why are TiO2 nanoparticles better than larger grains of TiO2 in sunscreen?

CORRECT ANSWER
Nanoparticles are cleaner than larger grains
EDDIE SAYS
Older sunscreens used larger particles of TiO2. These worked fine, but left stains. Nanoparticles are a bit better at absorbing sunlight, but their main benefit is that they don't stain as much.
  • Question 7

Which of these statements best describes the safety of nanoparticles?

CORRECT ANSWER
Nanoparticles seem to be safe, but we can't be sure
EDDIE SAYS
Most nanoparticles seem to be safe to use, and we have reason to think that many really are safe. The problem with anything new is that we can only be sure of their safety after many decades of use. There may be problems which only become clear after many years.
  • Question 8

Why do nanoparticles behave differently to larger particles of the same materials?

CORRECT ANSWER
Nanoparticles have much more surface area than bulk materials
EDDIE SAYS
Surfaces of any materials tend to behave differently to the inside of materials. The clever thing about nanoparticles is that almost all the material is surface.
  • Question 9

Which organ is most likely to be at risk from the effects of nanoparticles?

CORRECT ANSWER
lungs
EDDIE SAYS
We know that soot (which is fairly small particles of carbon) can cause people to have problems breathing. We don't know if the same goes for nanoparticles in general (which are smaller), but it's a risk that is being investigated.
  • Question 10

What is the name of this structure?

CORRECT ANSWER
nanotube
EDDIE SAYS
\"Tube\" because it is tube-shaped, \"Nano\" because it is a few nanometres across. Nanotechnology really started with carbon, because the bonding allows interesting shapes to be made.
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