Other large molecules

Question 1

What are graphene and fullerenes?

Answer 1

forms of carbon that exist as giant molecules

Question 2

Describe the structure of graphene

Answer 2

giant molecular substance, another form of carbon

structure resembles a single layer of graphite

each carbon atom covalently bonded to 3 others

regular hexagonal lattice structure

Question 3

properties of graphene and explanations

Answer 3

conducts electricity:

• non bonding outer electrons become delocalised and can move through the structure
• results in free, moving electrons that can carry electrical charge

strong and flexible:
-contains many strong covalent bonds

almost transparent:
-layers are just one atom thick

Question 4

Name and describe two types of fullerenes

Answer 4

-sheet of graphene rolled to form:

hollow balls (buckyballs)

• buckminsterfullerene, C60
• carbon atoms arranged in pentagons and hexagons

hollow tubes (carbon nanotubes)

• closed or open ends
• can be several mm long
• conduct heat effectively
• high tensile strength

Question 5

Describe and explain 2 properties of 2 different fullerenes

Answer 5

materials made from buckyballs:

• conduct electricity because they have delocalised electrons
• are soft/slippery when in the solid state because they have weak intermolecular forces

materials made from carbon nanotubes:

• conduct electricity as they have delocalised electrons
• are very strong because the structures have many strong covalent bonds

Question 6

List uses of fullerenes

Answer 6

nanotubes:
-used in tennis rackets to increase strength

• drugs can be placed inside fullerenes and delivered to target cells
• used with catalysts to increase surface area

Question 7

tensile strength

Answer 7

a measure of the amount of force needed to pull a material apart

Question 8

Describe the properties of graphene that make it suitable for use in flexible touch screens

Answer 8

almost transparent
flexible
conducts electricity

Question 9

Explain why buckminsterfullerene has a much lower melting point than diamond

Answer 9

not a giant molecular substance as they are made up of large molecules

weak intermolecular forces exist between buckminsterfullerenes

weak intermolecular forces are overcome on heating, but many strong covalent bonds need to be broken in diamond

there are many more bonds in diamond than buckminsterfullerene

Question 10

Describe the structural difference between graphene and fullerenes

Answer 10

graphene is not a fullerene

graphene is a giant covalent substance while fullerenes are large molecules

fullerenes have weak intermolecular forces between molecules while graphene does not