Graphite is the most common allatrope of pure carbon. It takes the form of a
black, soft solid. The structure is a comparatively weak one(Compared to Diamond), it is bonded in layers. This is one of the reasons for it being so soft.
These layers can slide past eachother with great ease, which makes it very useful
as a solid state lubricant. The most well known use for graphite is to make "Leads"
in pencils. In pencils the grapite is mixed with clay to change the hardness of the
"Lead".
The structure of graphite
Extraction of graphite.
Some countries have natural supplies of graphite. Others make it by heating coke and sand in an electric furnace.
The Structure of Graphite
As mentioned above graphite has a layered structure (See picture above), the approximate distance between
layers is 3.35 Angstroms. Because the separation of the layers is approximately the
Van Der Vaal's radii of C, then the layers should be weakly bonded to eachother. This accounts for
its low hardness. This is because the layers can slide over eachother easily.
Each carbon is bonded to three others, this is by Pi and Sigma bonds. It is these Pi bonds
which account for its high electrical conductivity.
What are its uses?
As mentioned above graphite is used as a solid state lubricant, also mentioned above it is a major constituent of pencil "leads".
Because of its good electrical conductivity, and relatively low reactivity it is useful to use as an electrode. A
more serious use for it is that it slows down neutrons in a nuclear reactor.
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