9.35-9.39 - Bulk and surface properties of matter including nanoparticles

Question 1

Compare the size of nanoparticles with the sizes of atoms and molecules

Answer 1

Nanoparticles are 1-100nm in size and usually contain a few hundred atoms. This means they are around a 100 times larger than atoms and simple molecules.

Question 2

Describe how the surface area to volume ratio of the particles that nanoparticles contain are related to their uses.

Answer 2

The large surface area to volume ratios of nanoparticulate substances allows them to act as catalysts.
Compared to the same substances in bulk, they may: catalyse reactions more efficiently; catalyse different reactions; produce different products.

As well, you need much less of a material made of nanoparticles than bigger particles due to the surface area

Question 3

State the uses of nanoparticles

Answer 3

-Sunscreen
-Tennis balls
-Socks
-Artificial hips
-Sports equipment
-Self-cleaning windows
-Lubricant coatings, as they reduce friction

Question 3

Describe advantages of nanoparticles other than their surface area to volume ratio

Answer 3

-Stronger than normal particles
-We can’t see them with the naked eye so they can produce transparent coatings e.g. for sunscreen to be less obvious
-Nanotubes conduct electricity, so can be used in small electrical circuits for computers

Question 4

Explain the possible risks associated with some nanoparticulate materials

Answer 4

-Small size makes them possible to breathe in or pass into cells.
-Once inside the body they might catalyse reactions that are harmful
-Toxic substances could bind to them due to their large surface area to volume ratios, harming health if the nanoparticles do get in the body
-They may be toxic to specific cells

Question 5

Describe the properties of glass ceramics

Answer 5

Glass is transparent and hard but brittle. It has a high melting point and conducts heat and electricity poorly.

Question 6

Describe the properties of clay ceramics

Answer 6

They include brick, china and porcelain.

They are often coated in a glaze which makes them hard, smooth, opaque and waterproof.

They have high melting points, are brittle and are poor conductors of electricity and heat.

Question 7

Describe the properties of polymers

Answer 7

They are poor conductors of electricity and heat. Their other properties depend on the type of polymer.

Question 8

Describe composites

Answer 8

Most composites have 2 components: the reinforcement and the matrix, which binds the reinforcement together.

Question 9

Describe the properties of metals

Answer 9

Metals are malleable, shiny, sonorous, lustrous and ductile and good conductors of heat and electricity.