Structure and Bonding (3)

Question 1

Explain why graphene is strong

Answer 1

As it is a giant lattice with strong covalent bonds

Question 2

Explain why graphite is a lubricant

Answer 2

As there are weak forces between molecules so layers can slide

Question 3

Explain why alloys are harder than pure metals

Answer 3

As atoms in an alloy are different sizes so layers are distorted and so they can slide less easily

Question 4

Describe, as fully as you can, the structure and bonding in diamond

Answer 4

Giant structure with strong covalent bonds where each carbon atom forms four bonds

Question 5

Describe the structure and bonding in a thermosoftening polymer and explain why thermosoftening polymers melt when heated

Answer 5

They are made up of chains with intermolecular forces that are weak meaning less energy is needed to overcome the forces.

Question 6

Suggest why a sheet of graphene which has a large number of carbon layers would not be suitable for the touchscreen

Answer 6

As layers slide

Question 7

Graphite is softer than diamond. Explain why

Answer 7

Layers of carbon atoms in graphite can move due to the weak intermolecular forces. However, in diamond, each carbon atom is strongly bonded to four others so no carbon atoms can move

Question 8

Explain why copper, like many other metals, has a high melting point

Answer 8

Giant structure with positive ions containing delocalised electrons. There are electrostatic attractions between the electrons and positive ions which require a lot of energy to overcome