Example - Ethane:
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What is the geometry for each carbon in CH3-CH3?
Draw a 3-dimensional
Carbon #1 has 4 atoms attached to it (3 H and 1 C) and carbon
#2 has 4 atoms attached to it. Therefore, around each carbon
will be tetrahedral . Since 3-D drawings are hard to make on
a flat surface as shown by the easy drawings on the upper and
middle left. These do not really tell you anything about the
3-D qualities of the molecule.
To make a 3-D drawing on paper, the molecule on the lower left
is a good representation. Bonds which "stick" out in
front or behind the plane of the paper are indicated with "wedges"
or dashed lines. "Thin" lines are in the plane of the
Finally look at the ball and stick model to see how the two
tetrahederals centered on each carbon overlap each other.