VSEPR - A Summary

Valence Shell Electron Pair Repulsion (VSEPR) theory allows fairly accurate prediction of the 3-dimensional shape of molecules from knowledge of their Lewis Dot structure. In VSEPR theory, the position of bound atoms (ligands) and electron pairs are described relative to a central atom. Once the ligands and lone pair electrons are positioned, the resulting geometrical shape presented by the atoms only (ignoring lone pairs) is used to describe the molecule.

Below is a table showing examples of the most common geometries encountered using the VSEPR theory. Clicking the cursor on the example molecules will allow you to view the 3-dimensional models. The lone pairs of electrons on the central atom are shown in pink as separate images.

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Total Number of Atoms + Lone Pairs


GEOMETRY


(No Central Atom)


Linear

O2    N2


With Lone Pairs

O2    N2


2


Linear

CO2  


3


Trigonal Planar

BF3


Bent

SO2

With Lone Pairs



4


Tetrahedral

CH4

 

Trigonal Pyramidal

NH3


Bent

H2O

With Lone Pairs


5

Trigonal Bipyramidal

PF5

See-saw

SF4

With Lone Pairs

T-Shaped

ClF3

With Lone Pairs

Linear

XeF2

With Lone Pairs


6


Octahedral
SF6

 

Square Pyramidal

BrF5

With Lone Pairs


Square Planar

XeF4

With Lone Pairs

 

 


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Last modified: rjr 1/15/12 at 12:01 PM