C2 Topic 2 covalent compounds and metals REVISION
Covalent bonding
1. Give three examples of simple molecules that
have covalent bonds (2marks)
2. Why do atoms share electrons?
3. What are diamond and silicone dioxide
examples of?
Simple molecules
4. Why don’t simple covalent molecules conduct
electricity?
5. Describe the melting and boiling points of
simple molecules
6. Describe the forces between simple
molecules
Giant covalent – diamond structure
7. Describe the properties of giant covalent
compounds
8. Name two examples of giant covalent
structures: (2marks)
9. Describe the properties of diamond (2marks)
10. Why does diamond have a high melting
point?
Giant covalent – graphite structure
11. How many bonds does each carbon in
graphite make?
12. Why can the layers slide over each?
13. Describe the properties of graphite
Any three from: H2, Cl2, O2, HCl, H2O,
NH3 and CH4
To gain full outer shells of electrons
Giant covalent structures
They have no free electrons
Very low
Very weak forces – easily overcome
They have very high melting points
Diamond and graphite
It has a very high melting point / it is
incredibly strong
It has 4 strong covalent bonds per
carbon atom
3 bonds per atom
There are only weak forces between
layers
Soft and slippery (used as a lubricant
in machinery).
Fullerenes and nanoscience
16. What is the formula of fullerene?
For drug delivery, in lubricants, as
catalysts, and in nanotubes
New catalysts, stronger and lighter
construction materials (e.g. tennis
racquets)
C60
17. What size are nanostructures?
1-100 nm
14. What are fullerenes used for? (2marks)
15. What new technology is nanoscience being
used to develop? (2marks)
Polymers
18. What are the two types of polyethene?
(2marks)
LD – low density, and HD – high
density
19. How are the reactions to produce polyethene They use different catalysts and
different? (2marks)
reaction condition
20. Why do thermosoftening melt easier?
They do not contain cross-links
21. Why do thermosetting not melt easily?
They contain cross-links
Metallic bonding
22.How are the atoms in metals arranged?
23.Describe the electrons in metals
Metallic properties
24.Explain why metals are able to be bent
and shaped
25.Describe how metals are able to conduct
heat and electricity
Alloys
Gaint metallic lattice
The outer electrons are delocalised and
so free to move throughout the
structure
The layers are able to slide
Because the delocalised electrons in
their structure are free to move
27.What are alloys made from?
 The layers in alloys are distorted
 due to be made up of different
sized metal atoms,
 and so are unable to slide over
each other easily
Mixture of metals
28.Give an example of an alloy
Steel – made from iron and carbon
26.Explain why alloys are harder than pure
metals (3marks)
29. Give an example of a shape memory alloy Nitinol – used in dental braces
30.Describe the properties of shape memory They are able to return to their original
alloys
shape after being deformed