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 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
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 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.
Atoms are represented by balls and bonds are represented as sticks.
THE 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.
following structures will require you to download a molecular
modeling viewer to view the pdb files. We highly reccommend you
take a look at "Viewing Molecules at
Home and School" and download a software package.