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Chemical Reactions > Bonding v



Valence Shell Electron Pair Repulsion Theory
    

1. Find the central atom. Determine which orbitals are available for hybridization.
2. Count the valence electrons and add the electrons to account for the overall charge and the electrons donated by bonded atoms (one for each single bond, two for each double bond, etc).
3. Divide the result by 2 to get the total number of electron pairs. For unusual compounds in which have an odd number of total electrons, count the unpaired electron as an electron pair. Determine the number of lone pairs by

4. Minimize the electron pair-electron pair repulsion according to

This will mean that the linear geometry is favored for 5 pairs and 3 lone pairs, while the T-shaped is favored for 5 pairs and 2 lone pairs.

5. The arrangement is given by the total number of electron pairs, and the molecular geometry class by the number of lone pairs.

prs. arrangement lone pr. molecular geometry hybridization
2 linear 0 linear sp
3 trigonal 0 trigonal planar  
  planar 1 bent  
4 tetrahedral 0 tetrahedral , , ,
    1 trigonal pyramidal  
    2 bent  
    3 linear  
5 trigonal 0 trigonal bipyramidal
  bipyramidal 1 distorted pentahedral  
    2 T-shaped  
    3 linear  
6 octahedral 0 octahedral
    1 square base pyramidal
    2 square planar
7 pent. bipyramidal 0 pentagonal bipyramidal  
species central bond total pairs lone geometry
I 7 2+1 10 5 3 linear
ICl3 7 3 10 5 2 T-shaped
IF5 7 5 12 6 2 square planar
PCl3F2 5 5 10 5 0 trigonal bipyramidal
PF3 5 3 8 4 1 trigonal pyramidal
SF2 6 2 8 4 2 bent
SO3 6 3 9 5 2 T-shaped
TeH2 6 2 8 4 2 bent






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