Shapes of Molecules and Ions with Double or Triple Bonds
The presence of double or triple bonds does not complicate matters at all. In a double bond, both electron pairs must stay together between the two atoms; they can't wander off to different locations in the valence shell. This is also true for the three pairs of electrons in a triple bond. For the purposes of predicting molecular geometry, then, we can treat double and triple bonds just as we do single bonds. For example, the Lewis formula for CO2 is
 
         ..         ..
         O=C=O
         ..         ..
 
The carbon atom has no lone pairs. Therefore, the two groups of electron pairs that make up the double bonds are located on opposite sides of the nucleus and a linear molecule is formed. Similarly, you should be able to predict the following shapes for SO2 and SO3
 
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