Carbon is found in many different compounds. It
is in the food you eat, the clothes you wear, the cosmetics you use and the gasoline
that fuels your car. In addition, carbon is a very special element because it
plays a dominant role in the chemistry of life.
Carbon has four electrons in its valence shell (outershell).
Since this energy shell can hold eight electrons, each carbon atom can share electrons
with up to four different atoms. Carbon can combine with other elements as well
as with itself. This allows carbon to form many different compounds of varying
size and shape.
Carbon alone forms the familiar substances graphite and diamond.
Both are made only of carbon atoms. Graphite is very soft and slippery. Diamond
is the hardest substance known to man. If both are made only of carbon what gives
them different properties? The answer lies in the way the carbon atoms form bonds
with each other.
Notice that graphite is layered.
on image for VRML
There are strong covalent bonds between carbon
atoms in each layer. But, only weak forces exist between layers. This allows layers
of carbon to slide overeach other in graphite.
On the other hand, in diamond
each carbon atom is the same distance to each of its neighboring carbon atoms.
In this rigid network atoms cannot move. This explains why diamonds are so hard
and have such a high melting point.
Click on image for VRML
The 3-D coordinates for graphite and
diamond are available in the MathMol
Structural Database. We urge you to download these structures to your home
computer and use one of the suggested 3-D viewers.
The Molecule of the Month
Page has recently included information on diamond located here
A third class of carbon compounds has recently been discovered. They
are called fullerenes. The figure shown on the left is one form composed of 60
carbons. Notice the geometric patterns of pentagons and hexagons that form the
Click on the image for VRML
A java applet that shows the fullerene and allows rotation of the image
is now available here.
2: Compounds made of Carbon