C2.3 Properties Of Material Flashcards
Why are metals malleable?
Metals are malleable because it has a sea of delocalised electrons. So when a large enough external force is applied the arrangement of particle can change by bending as since the eco trona are free to move around the electrostatic forces are still holding the particles together so no bonds are broken.
What happens to the forces of attraction when a substance goes from the solid state to the liquid state?
Some of the bonds break
The stronger the forces/bonds and the more there are…
the more energy will be required to break these forces/bonds.
Uses of nanoparticles
- They have a large surface area to volume ratio so they can make good catalysts.
- New cosmetic, eg.sun creams and deodorants, have been made using nanoparticles. The small particles do their job but they don’t leave white marks.
- Nanomedicine. The idea is that tiny fullerenes are observed more easily by the body than most particles. This means they can deliver drugs right into the cells where they are needed.
- New lubricant coatings are being developed using fullerenes. These coatings reduce friction a bit like really tiny ball bearings an could be used in all sort of places from artificial joints to gears.
- Nanotubes conduct electricity, so they can be used in tiny electric circuits for computer chips.
- Nanoparticles are added to plastics in sports equipment to make the plastic much stronger and more durable, without adding much mass.
- Silver nanoparticles are added to polymer fibres used to make surgical masks and wounds dressings. This gives the fibres antibacterial properties.
Polymers Giant covalent structure Metallic bonding Simple covalent structures Giant ionic lattices Put these in order from highest boiling to point to lowest
Giant covalent structure Giant ionic lattices Metallic bonding Polymers Simple covalent structures
When do bonds form in a substance?
When a substance condenses or freezes
Gas to liquid state. Describe the bonds
Some bonds form
What is a nanoparticulate?
It is a material made from nanoparticles
Where the does the energy go when a substance melts or boils
This energy comes from the surroundings into the substance to overcome the forces of attraction
Sublimation
When a substance changes directly from the solid state to the gas state.
Eg. Iodine. It exists as a simple molecule
What is the opposite of sublimation?
Deposition
How can a substance conduct electricity?
A substance can conduct electricity if it has charged particles that are free to move.
What happens to the forces of attraction when a substance goes from the liquid state to the gas state?
All the remaining bonds break
What is a nanoparticle?
A nanoparticle is a particle between 1nm and 100nm across, and consists of just a few hundred atoms.
Risks of nanoparticles
They are so tiny that they can be breathed in, absorbed by the skin or pass into cells
They take a long time to break down once released into the environment and toxic substances may stick to them
Risks are difficult to determine
