C2.2 - How Structure Influences Properties And Uses Flashcards
When a simple molecular substance melts or boils, which forces are broken?
The intermolecular forces.
Why don’t simple molecular substances conduct electricity?
The molecules are not charged.
What do ionic compounds have as a result of their strong bonds?
High melting and boiling points.
When do ionic compounds conduct electricity and why?
When they are molten or dissolved in water, as the ions are free to move and carry the current.
How many covalent bonds does each carbon atom form in diamond?
Four.
How many covalent bonds does each carbon atom form in graphite?
Three.
Which allotrope of carbon will conduct electricity and heat and why?
Graphite, because each carbon atom has a delocalised electron.
What is silica a giant structure of?
Silicon and oxygen.
Why is graphite soft and slippery?
Because the atoms are arranged in layers that are able to slide over each other.
What are the intermolecular forces like between the layers in graphite?
Weak.
In fullerenes, what shape are carbon atoms arranged in?
Hexagons.
What are some uses for fullerenes? (4)
- Drug delivery into the body.
- Catalysts.
- Lubricants.
- In nanotubes for reinforcing materials.
What is different in different types of fullerenes?
The number of carbon atoms.
How many carbon atoms are in buckminsterfullerene molecules, and in what shape?
60 carbon atoms in a spherical molecule.
What do allotropes of carbon form when they burn in oxygen?
Carbon dioxide.
Why do metals conduct heat and electricity?
Because of their delocalised electrons.
Why can metals be easily shaped?
The layers of atoms are able to slide over each other.
What are alloys made from?
Two or more metals.
Why are alloys less easily shaped than metals?
The different sized metal atoms distort the layers.
What can shape memory alloys do?
Return to their original shape after being deformed.
What shape memory alloy is used in braces?
Nitinol.
Under what conditions are low density polymers made?
Heating ethene at about 200 degrees under high pressure.
Under what conditions are high density polymers made?
Heating ethene at a low temperature and pressure with a catalyst.
What are the properties of thermosoftening polymers? (5)
- Made up of individual tangled chains of polymers.
- Weak intermolecular forces.
- The chains can slide over each other.
- Low melting points.
- Easily re-shaped.
What are the properties of thermosetting polymers? (4)
- Strong intermolecular forces.
- Polymer chains called crosslinks hold the chains together.
- A solid structure.
- Strong/rigid/hard.
What size are the structures referred to in nanoscience?
Between 1 and 100 nanometres.
What is the surface area to volume ratio in nanoparticles like?
High.
How are nanoparticles used in the cosmetic industry?
In sun tan creams and deodorants.
What are the uses of nanoparticles? (5)
- Computers.
- Catalysts.
- Cosmetics.
- Construction.
- Coatings.
What are the properties of substances that consist of simple molecules?
Low melting and boiling points.
