The simplest organic compounds contain molecules composed of
carbon and hydrogen. The compound methane contains one carbon
bonded to four hydrogens. Ethane is another example of a simple
hydrocarbon. Ethane contains two carbon atoms and six 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
Although structural 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 three different representation to show what molecules
THE 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 BALL-AND-STICK MODEL
Atoms are represented by balls and bonds are represented as sticks.
SPACE FILLED MODEL
This 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.
For a more complete list of carbon
compounds see the MathMol
Library of Molecules.