Bulk & Surface Properties of Matter Including Nanoparticles

What is the name for the study of structures that are between 1 and 100 nanometres (nm) in size?

Nanoscience.

What is the typical size range for nanoparticles?

They have a diameter between 1 and 100 nanometres (nm).

Approximately how many atoms make up most nanoparticles?

A few hundred atoms.

What are coarse particles (PM10) often referred to as?

Dust.

What is the diameter range for coarse particles, also known as PM10 or dust?

Between 2,500 and 10,000 nm.

What is the diameter range for fine particles, also known as PM2.5?

Between 100 and 2,500 nm.

Compared to the same material in bulk, nanoparticles have a very large _____ to _____ ratio.

Surface area to volume.

What happens to the surface area to volume ratio of a cube-shaped particle if the length of its side decreases by a factor of 10?

The surface area to volume ratio increases by a factor of 10.

Why do the properties of a nanoparticulate substance differ from the same substance in bulk?

Due to their tiny size and their very large surface area to volume ratio.

What property of nanoparticulate materials allows them to be very effective catalysts?

Their large surface area to volume ratio.

Why might a smaller quantity of nanoparticles be needed to be an effective catalyst compared to the same material with normal particle sizes?

Because of their high surface area to volume ratio, which means more surface is exposed for the reaction.

Name one medical application of nanoparticles.

They are used for medical treatments, such as delivering drugs into the body.

How can fullerenes be used in nanomedicine?

They can be formed into cage-like structures to deliver drugs to specific areas of the body.

Why is nanoparticulate zinc oxide preferred over bulk zinc oxide in sunscreens?

Nanoparticulate zinc oxide is invisible on the skin, whereas bulk zinc oxide is white.

What is a potential disadvantage of using invisible nanoparticulate sunscreen?

It may be difficult to tell where the sunscreen has been applied on the skin.

What technology are nanotubes, with their ability to conduct electricity, useful for?

Nanotechnology and electronics, such as in tiny electrical circuits for computer chips.

What coating on self-cleaning window panes catalyses the breakdown of dirt in sunlight?

A nanoparticulate coating.

What is a major concern regarding the health effects of nanoparticles?

Their small size makes it possible to breathe them in or for them to pass into cells, with unknown long-term effects.

Once inside the body, what is a potential risk of nanoparticles catalysing reactions?

They might catalyse reactions that are harmful to the body.

How could the large surface area to volume ratio of nanoparticles pose a health risk if they enter the body?

Toxic substances could bind to them, which would then be carried into the body, causing harm.

Why is it difficult for scientists to determine the long-term risks of modern nanoparticulate materials?

Because they have only become common recently, so there is limited data on their long-term effects.

Nanoparticulate silver is used in wound dressings for its antibacterial properties. What is a possible environmental hazard of this?

When the dressings are discarded, the silver nanoparticles could harm or kill useful bacteria in the environment.

What term describes molecules of carbon with hollow shapes, such as spheres and tubes?

Fullerenes.

What type of carbon rings are the structures of fullerenes primarily based on?

Hexagonal rings of carbon atoms.

What was the first fullerene to be discovered, which has a spherical shape and the formula C₆₀?

Buckminsterfullerene.

What type of forces exist between molecules of buckminsterfullerene?

Weak intermolecular forces.

Why does buckminsterfullerene have a low melting point and a slippery texture?

Because little energy is needed to overcome the weak intermolecular forces between its molecules.

What are carbon nanotubes?

Cylindrical fullerenes that can be thought of as a layer of graphene rolled into a cylinder.

What structural feature of carbon nanotubes makes them useful for reinforcing materials without adding much weight?

They have a high length to diameter ratio (they are very long and thin).

Why are carbon nanotubes strong in tension (have high tensile strength)?

Because of the strong covalent bonds between the carbon atoms.

Why can both graphene and carbon nanotubes conduct electricity?

Because they have delocalised electrons that are free to move and carry charge.

Name one use for carbon nanotubes that takes advantage of their high tensile strength.

Reinforcing materials, such as in tennis racket frames.

What is graphene?

A single layer of graphite, consisting of carbon atoms in hexagonal rings.

Why is graphene very strong and has a very high melting point?

Due to the strong covalent bonds between its carbon atoms.

Give an example of a use for fullerenes that takes advantage of their large surface area to volume ratio.

They can be used as industrial catalysts to speed up chemical reactions.

Name a use for fullerenes besides drug delivery and catalysts.

They can be used as lubricants.

_____ are molecules of carbon atoms with hollow shapes, often based on hexagonal rings.

Fullerenes.

The first fullerene discovered was _____, which has the formula C₆₀.

Buckminsterfullerene.

Cylindrical fullerenes with very high length to diameter ratios are known as _____.

Carbon nanotubes.

The properties of nanoparticles are different from bulk materials due to their small size and high _____ ratio.

Surface area to volume.

Nanoparticles used in sunscreens are effective because they provide better _____ and protection against UV rays.

Skin coverage.

A potential risk of nanoparticles is that their long-term effects on _____ are not yet fully understood.

Our bodies.

What term refers to tiny particles with a diameter between 100 nm and 2,500 nm?

Fine particles.

What is the diameter of an average atom or small molecule, for comparison with nanoparticles?

Approximately 0.1 nm.