Structure and bonding of carbon (2.3) (M)

Question 1

Describe the composition of diamond?

Answer 1

In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure

Question 2

3 properties needed

What does diamond’s composition mean for its properties?

Answer 2

• very hard (strong covalent bonds)
• very high melting point (strong covalent bonds)
• doesn’t conduct electricity (no free electrons to carry electrical charge)

Question 3

Describe the composition of graphite

Answer 3

In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings which have no covalent bonds between the layers (weak force of attraction between them)

one electron from each carbon atom is delocalised

Question 4

How is graphite similar to metals?

Answer 4

They both have delocalised electrons

Question 5

What are the properties of graphite?

Answer 5

• very high melting/boiling point (strong covalent bonds need lots of energy to overcome)
• strong electrical conductivity (delocalised electron can carry electrical charge)
• softness (weak forces between layers allow them to slide)

Question 6

What does a model of graphite look like?

Answer 6

Question 7

What are the uses of graphite?

Answer 7

used as a lubricant (as it is slippery) and in pencils

Question 8

What are graphenes and fullerene a form of?

Answer 8

forms of carbon

Question 9

What is graphene?

Answer 9

a single layer of graphite

Question 10

graphene has (…) covalent bond between atoms

Answer 10

strong

Question 11

What are the properties of graphene?

Answer 11

• very high melting point
• very strong
• conducts electricity

Question 12

What are graphene’s uses?

Answer 12

• electronics
• composites

Question 13

What are composites?

Answer 13

Material made from multiple material with contrasting properties

Question 14

What are fullerenes?

Answer 14

molecules of carbon atoms with hollow shapes

Question 15

What are two examples of fullerenes?

Answer 15

buckminsterfullerene and carbon nanotubes

Question 16

What is the structure of fullerenes?

Answer 16

based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms

Question 17

What was the first fullerene to be discovered?

Answer 17

Buckminsterfullerene

Question 18

What is the formula of Buckminsterfullerene?

Answer 18

C₆₀

Question 19

What is the shape of Buckminsterfullerene?

Answer 19

has a spherical shape

Question 20

What is the difference in terms of structure between graphene and fullerenes?

Answer 20

Graphene has a giant covalent structure, but fullerenes have large molecules.

Question 21

Buckminsterfullerene has one (…) electron per atom of carbon that can move freely between layers so it can conduct electricity as the delocalised electron carries an electrical charge

Answer 21

delocalised

Question 22

What are the properties of buckminsterfullerene?

Answer 22

• slippery
• low melting point (weak intermolecular forces)

fullerenes not giant covalent

Question 23

What does buckminsterfullerene look like?

Answer 23

Question 24

What are carbon nanotubes?

Answer 24

cylindrical fullerenes with very high length to diameter ratios

Question 25

2 needed

What are the properties of carbon nanotubes?

Answer 25

• high tensile strength
• high electrical/thermal conductivity

Question 26

3 needed

What are the uses of carbon nanotubes?

Answer 26

• nanotechnology
• electronics
• specialised materials (e.g. a tennis racket)

Question 27

3 needed

What are some uses of diamond?

Answer 27

• jewellery
• for cutting tools and blade edges
• to make diamond tipped drill bits

Question 28

Why is buckminsterfullerene a good lubricant?

Answer 28

• molecules are spherical
• so molecules will role

Question 29

Why are nanotubes good lubricants?

Answer 29

nanotubes can slide over each other

because there are no covalent bonds between the nanotubes (accept weak intermolecular forces)

Question 30

2 marks - low demand

Why is diamond hard?

Answer 30

has a giant structure with strong bonds

Question 31

Why is graphite softer than carbon?

Answer 31

In graphite the layers can slide as there are weak intermolecular forces between the layers

However in diamond, each carbon atom is (strongly/covalently) bonded to 4 others, so atoms are not able to move/slide

Question 32

4 marks

Why is silicon dioxide suitable for lining furnaces?

Answer 32

Silicon dioxide has a giant covalent structure

with strong bonds

a lot of energy is needed to break these bonds

so silicon dioxide has a high melting point

Question 33

Why does graphite conduct electricity?

Answer 33

Graphite has delocalised electrons (each carbon atom is covalently bonded to 3 others, so there is 1 delocalised electron per carbon atom)

that can move freely through the whole structure of graphite

and carry a charge

model answer