diamond, graphite, fullerenes and nanoparticles (topic 2)

Question 1

graphite is softer than diamond, explain why (4)

Answer 1

graphite:
- the layers of carbon atoms in graphite can move
- because there are only weak intermolecular forces between layers
diamond:
- each carbon atom is strongly bonded to 4 others
- no carbon atoms are able to move

Question 2

graphite conducts electricity, but diamond does not, explain why (3)

Answer 2

graphite:
- has delocalised electrons
- which can carry charge
diamond:
- has no delocalised electrons

Question 3

(3)

Answer 3

• graphite made from layers of carbon atoms
• weak intermolecular forces between layers
• so layers can slide over each other

Question 4

(3)

Answer 4

• giant structure
• each carbon atom is joined to four others
• by covalent bonds
• bonds are strong
• it takes a lot of energy to break bonds

Question 5

(3)

Answer 5

• giant lattice
• atoms in graphene are covalently bonded
• covalent bonds are strong

Question 6

explain why graphene can conduct electricity (2)

Answer 6

• graphene has delocalised electrons
• which can move throughout the structure

Question 7

suggest why a block of graphite, which has a large number of graphene sheets, could not be used for a touchscreen (1)

Answer 7

• opaque
• layers would slide

Question 8

explain why carbon nanotubes are very strong (1)

Answer 8

• the carbon atoms are held together by strong covalent bonds

Question 9

explain why diamond is hard (3)

Answer 9

• giant structure
• each carbon atom forms 4 covalent bonds
• covalent bonds are strong

Question 10

explain why graphite is slippery (2)

Answer 10

• weak forces of attraction between layers
• layers of atoms can slide over each other

Question 11

Answer 11

Question 12

explain why diamond has a high melting point (4)

Answer 12

• large number of covalent bonds
• between atoms
• covalent bonds are strong
• large amount of energy required to break bonds

Question 13

describe the structure and bonding in diamond (3)

Answer 13

• giant structure
• strong covalent bonds between carbon atoms
• each carbon atom forms 4 bonds

Question 14

(6)

Answer 14

graphite conducts electricity because (max 3 marks):
- bonds are covalent
- graphite has a giant structure
- three covalent bonds per carbon atom
- so one electron (per carbon atom) is delocalised
- delocalised electrons move freely through the structure
- delocalised electrons carry electrical charge
graphite is soft and slippery because (max 3 marks):
- it has a layered structure
- of (interlocking) hexagonal rings
- weak intermolecular forces between layers
- so layers can slide over each other

Question 15

suggest why Buckminsterfullerene is a good lubricant (2)

Answer 15

• molecules are spherical
• so molecules will roll

Question 16

suggest two reasons why Buckminsterfullerene is suitable in medicine to move drugs around the body (2)

Answer 16

• it is hollow
• it is unreactive
• it is not toxic
• it has a large surface area to volume ratio

Question 17

give one other use of a fullerene such as Buckminsterfullerene other than in medicine to move drugs around the body (1)

Answer 17

• hydrogen storage
• anti-oxidant
• reduction of bacterial growth
• catalyst

Question 18

what are nanoparticles (1)

Answer 18

particles of size 1-100 nm

Question 19

Answer 19

coarse particle

Question 20

Answer 20

Question 21

suggest why it is cheaper to use nanoparticles of silver rather than coarse particles of silver (2)

Answer 21

• nanoparticles have a larger surface area to volume ratio
• so less can be used for the same effect

Question 22

give one possible risk of using nanoparticles (1)

Answer 22

• damages cells
• heart problems
• get into the bloodstream
• harmful to aquatic life

Question 23

how does the size of a nanoparticle compare with the size of an atom

Answer 23

• nanoparticles are larger (nanoparticles are the size of a few hundred atoms)

Question 24

Answer 24

100 times

Question 25

explain why nanoparticles pass through the skin and travel around the body more easily than normal-sized particles of titanium oxide

Answer 25

• nanoparticles are smaller
• so can easily pass through skin

Question 26

suggest two reasons why it may be necessary to test mineral sun creams further (2)

Answer 26

• may be toxic to cells
• to ensure safety
• to see if they pass into the body

Question 27

suggest two reasons why companies that make mineral sun creams may be reluctant to carry out further tests.