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
14. HT - How is graphite able to conduct heat
and electricity?
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 intermolecular
forces between layers
Soft and slippery (used as a lubricant
in machinery).
Due to having one delocalised
electron per carbon atom that is
able to move through the structure
Fullerenes and nanoscience
17. 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
18. What size are nanostructures?
1-100 nm
15. What are fullerenes used for? (2marks)
16. What new technology is nanoscience being
used to develop? (2marks)
Polymers
19. What are the two types of polyethene?
(2marks)
20. How are the reactions to produce polyethene
different? (2marks)
21. Describe thermosetting polymers
22. Why do thermosoftening melt easier?
23. Describe thermosoftening polymers
LD – low density, and HD – high
density
They use different catalysts and
reaction condition
They consist of polymer chains with
cross-links
They do not contain cross-links
They consist of individual, tangled
polymer chains
Metallic bonding
24.How are the atoms in metals arranged?
25.Describe the electrons in metals
Metallic properties
26.Explain why metals are able to be bent
and shaped
27.Describe how metals are able to conduct
heat and electricity
Alloys
28.Explain why alloys are harder than pure
metals (3marks)
29.What are alloys made from?
30.Give an example of an alloy
In a giant, regular structure of positive
ions surrounded by a sea of delocalised
electrons
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
 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
Two or more elements mixed together,
one of which must be a metal
Steel – made from iron and carbon
31. Give an example of a shape memory alloy Nitinol – used in dental braces
32.Describe the properties of shape memory They are able to return to their original
alloys
shape after being deformed