4.2.3 Structure and bonding of carbon

Question 1

Describe the structure of diamond

Answer 1

Each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure

Question 2

Explain why diamond is very hard

Answer 2

Many strong covalent bonds between the atoms

Question 3

Explain why diamond has a very high melting point

Answer 3

Many strong covalent bonds between the atoms so lots of energy is needed to break these

Question 4

Explain why diamond does not conduct electricity

Answer 4

No electrons or ions are free to move

Question 5

Describe the structure of graphite

Answer 5

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. 1 electron from each carbon atom is delocalised.

Question 6

Explain why graphite is soft

Answer 6

No covalent bonds between the layers so can slide past each other easily.

Question 7

Explain why graphite has a very high melting point

Answer 7

Many strong covalent bonds between the atoms so lots of energy is needed to break these

Question 8

Explain why graphite conducts electricity

Answer 8

Delocalised electrons can move throughout the structure and carry a charge

Question 9

Explain why graphite is similar to a metal

Answer 9

Because it has delocalised electrons

Question 10

Describe the structure of graphene

Answer 10

Single layer of graphene.

Question 11

Explain why graphene is useful in electronics

Answer 11

Delocalised electrons and is see-through.

Question 12

Define a composite material

Answer 12

Materials formed by combining two or more materials together with different properties

Question 13

Explain why graphene is useful in composites

Answer 13

Strong and light

Question 14

Describe the structure of fullerenes

Answer 14

Molecules of carbon atoms with hollow shapes. The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms. The first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape. Carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios.

Question 15

Explain why spherical fullerenes are useful in medicine

Answer 15

To deliver medicines into the body inside the hollow shape

Question 16

Explain why carbon nanotubes are useful in electronics

Answer 16

Conduct electricity due to delocalised electrons

Question 17

Explain why carbon nanotubes are useful in materials

Answer 17

Strongest and stiffest materials that we have discovered due to strong covalent bonds between carbon atoms

Question 18

Explain why graphite and fullerenes are used as lubricants

Answer 18

Layers can slide or fullerenes can roll, reducing friction