Molecular Geometry Guide
ELECTRON REGIONS
SHAPE
MOLECULAR GEOMETRY
2
Electronic geometry =
linear
Linear
Hybridization: sp
[no lone pairs]
3
Electronic geometry =
trigonal planar
Trigonal planar
Hybridization: sp2
ELECTRON REGIONS
[no lone pairs]
SHAPE
MOLECULAR GEOMETRY
Tetrahedral
[no lone pairs]
4
Electronic geometry =
tetrahedral
Trigonal pyramid
Hybridization: sp3
[1 lone pair]
Bent (angular)
[2 lone pairs]
ELECTRON REGIONS
SHAPE
MOLECULAR GEOMETRY
Trigonal bipyramid
[no lone pairs]
See-saw
5
Electronic geometry =
trigonal bipyramid
[1 lone pair]
Hybridization: sp3d
T-shape
[2 lone pairs]
Linear
[3 lone pairs]
ELECTRON REGIONS
SHAPE
MOLECULAR GEOMETRY
Octahedral
[no lone pairs]
6
Electronic geometry =
octahedral
Hybridization: sp3d2
Square pyramidal
[1 lone pair]
Square planar
[2 lone pairs]
Polarity is determined by the electron regions around the central atom. If the regions are
identical and everything is symmetrical then the molecule is most likely non-polar. However, if
the regions are NOT identical or the molecule is NOT symmetrical the molecule is most likely
polar. The importance of polarity determines the phase change temperatures of molecules
(melting point, boiling point, etc.) and solubility (whether or not the molecule is soluble or
insoluble in certain substances). The rule of thumb for solubility is “like dissolves like” –
nonpolar substances dissolve in nonpolar solvents while polar substances dissolve in polar
substances. Water will dissolve most ionic salts and polar molecules.