Chemistry Reference
In-Depth Information
Table 3.8
Uses of graphite and diamond.
is present on each carbon atom. These 'spare' (or
delocalised
) electrons form electron clouds between
the layers and it is because of these spare electrons
that graphite conducts electricity.
In recent years a set of interesting compounds known
as
graphitic compounds
have been developed. In these
compounds different atoms have been fitted in between
the layers of carbon atoms to produce a substance with
a greater electrical conductivity than pure graphite.
Graphite is also used as a component in certain sports
equipment, such as tennis and squash rackets.
Graphite
Diamond
Pencils
Jewellery
Electrodes
Glass cutters
Lubricant
Diamond-studded saws
Drill bits
Polishers
Graphite
Figure 3.32a shows the structure of graphite. This is a
layer structure. Within each layer each carbon atom is
bonded to three others by strong covalent bonds. Each
layer is therefore like a giant molecule. Between these
layers there are weak forces of attraction (van der Waals'
forces) and so the layers will pass over each other easily.
With only three covalent bonds formed between
carbon atoms within the layers, an unbonded electron
Graphene
Discovered in 2004, graphene is a so-called super
material made up of single layers of graphite as shown
in the upper diagram of Figure 3.32a. It is able to
conduct electricity one million times better than copper
metal and has enormous potential in electronics.
Diamond
Figure 3.33a shows the diamond structure. Each of
the carbon atoms in the giant structure is covalently
bonded to four others. They form a tetrahedral
arrangement similar to that found in silicon(
iv
) oxide
(p. 50). This bonding scheme gives rise to a very
one layer
showing how the layers fit together
a
A portion of the graphite structure.
b
A piece of graphite as imaged through a scanning tunnelling
microscope.
Figure 3.32
