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follow page requires only that your computer be java ready. The molecules can
be rotated, zoomed-in/out and viewed as either wireframe, sticks, ball and stick
or space-filled models.
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. The element carbon has four electrons in its valence shell (outer shell).
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.
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.
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 over each 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.
Notice the strong bonding network
The 3-D coordinates
for graphite and diamond are available in the MathMol
Molecular Modeling Database. We urge you to download these structures
to your home computer and use one of the suggested 3-D Molecular Modeling Software
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 chime model shown below is one form composed of 60 carbons. Notice the geometric
patterns of pentagons and hexagons that form the familiar icosohedron.
Notice the geometric patterns of pentagons and hexagons
that form the familiar icosohedron.
made of Carbon
simplest organic compounds contain molecules composed of carbon and hydrogen.
The compound methane contains one carbon bonded to four hydrogen's. Ethane is
another example of a simple hydrocarbon. Ethane contains two carbon atoms and
four hydrogen atoms. In chemistry we use a molecular formula to show how many
atoms of each element are present in a molecule. A molecular formula however does
not show the structure of the molecule. Scientists often use structural formulas
to show the number and arrangement of atoms in a compounds. Below the molecular
formula for methane and ethane are shown. Above the molecular formula are their
respective structural formula.
formulas can be very helpful they do not give a complete picture of a molecule.
Structural formulas do not tell us anything about the distances between bonds,
the angles formed by these bonds, or the size and shape of the molecule. Scientists
use four different representation to show what molecules look like.
WIRE FRAME MODEL
This model clearly shows the type of atoms in the molecule, the distances between
bonds, and angles associated with the atoms. Because the lines drawn are very
thin, molecules can very easily be manipulated when viewed on a computer screen.
THE STICK MODEL
Atoms and bonds
are represented as sticks.
are represented by balls and bonds are represented as sticks.
SPACE FILLED MODEL
model shows the space that the molecule will take up. Because of all the points
required to draw this molecule on a computer screen you should expect these molecules
to be very difficult to manipulate.
Wire frame Model
Ball and Stick Model
Space Filled Model