c
Carbon is capable of forming many allotropes due to its valency.
Diamond is a well known allotrope of carbon. The hardness and high dispersion of light of diamond make it useful for both industrial applications and jewelry. Diamond is the hardest known natural mineral. This makes it an excellent abrasive and makes it hold polish and luster extremely well. No known naturally occurring substance can cut (or even scratch) a diamond, except another diamond.
Graphite, named by
Abraham Gottlob Werner in 1789, from the Greek γράφειν (
graphein, "to draw/write", for its use in pencils) is one of the most common allotropes of carbon. Unlike diamond, graphite is an electrical conductor. Thus, it can be used in, for instance, electrical arc lamp electrodes. Likewise, under
standard conditions, graphite is the most stable form of carbon. Therefore, it is used in thermochemistry as the
standard state for defining the
heat of formation of carbon compounds.
Graphite
conducts electricity, due to
delocalization of the
pi bond electrons above and below the planes of the carbon atoms. These electrons are free to move, so are able to conduct electricity. However, the electricity is only conducted along the plane of the layers.
Graphene
A single layer of graphite is called
graphene and has extraordinary electrical, thermal, and physical properties. It can be produced by
epitaxy on an insulating or conducting substrate or by mechanical exfoliation (repeated peeling) from graphite. Its applications may include replacing
silicon in high-performance electronic device.
The
buckminsterfullerenes, or usually just
fullerenes or
buckyballs for short, were discovered in 1985 by a team of scientists from Rice University and the University of Sussex, three of whom were awarded the 1996 Nobel Prize in Chemistry. They are named for the resemblance of their allotropic structure to the geodesic structures devised by the scientist and architect
Richard Buckminster "Bucky" Fuller. Fullerenes are molecules of varying sizes composed entirely of carbon, which take the form of a hollow sphere, ellipsoid, or tube.
