AX3 and AX2E Configurations
Molecules in this category may have three or four atoms.  The configuration is specified as AX3 for the case with four total atoms and AX2E for the case with only three atoms.  The "E" represents the electron group that is not involved in bonding.  Molecules of the type AX3 are trigonal planar and molecules of the type AX2E are bent.
Example AX3 Molecules (Trigonal Planar)
BF3 Rotatable 3-D image in browser
 RasMol file
CO32-
Note that there are 
two additional 
resonance structures; 
thus all the oxygen are 
equivalent. 		 Rotatable 3-D image in browser
 RasMol file
SO3 Rotatable 3-D image in browser
 RasMol file

 
 
 
Example AX2E Molecules (bent)
SO2 SO2 lewis structure
The bottom structure is the best based on the formal charges (small numbers next to each atom).
 Rotatable 3-D image in browser RasMol file

Last updated: March 13, 2007
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