MOLECULAR MODELS (Relationship of Molecular Shape to Electron Pair Geometry)

Relationship of Molecular Shape to Electron Pair Geometry

The following table summarizes the interrelationships between the number of groups of electrons around a central atom, the molecular shape around the central atom, and the electron pair geometry around the central atom. Note that the number of unshared electron pairs that may be associated with the central atom are indicated.

A Summary of Molecular Shape and Electron Pair Geometry

No. of groups of electrons around a central atom Electron pair geometry Angles between groups of electrons No. of unshared electron pairs Molecular shape Diagram Example

2 linear 180^o 0 linear CO₂

3 trigonal planar 120^o 0 trigonal planar BCl₃

3 trigonal planar 120^o 1 bent SO₂

4 tetrahedral 109.5^o 0 tetrahedral CI₄

4 tetrahedral 109.5^o 1 pyramidal PCl₃

4 tetrahedral 109.5^o 2 bent H₂S

4 tetrahedral 109.5^o 3 linear HBr

Created and maintained by: Dr. Anna Cavinato anna.cavinato@eou.edu and Dr. David Camp
.
All Material Copyright Eastern ChemWeb, Eastern Oregon University, 2003.

No. of groups of electrons around a central atom	Electron pair geometry	Angles between groups of electrons	No. of unshared electron pairs	Molecular shape	Diagram	Example
2	linear	180^o	0	linear		CO₂
3	trigonal planar	120^o	0	trigonal planar		BCl₃
3	trigonal planar	120^o	1	bent		SO₂
4	tetrahedral	109.5^o	0	tetrahedral		CI₄
4	tetrahedral	109.5^o	1	pyramidal		PCl₃
4	tetrahedral	109.5^o	2	bent		H₂S
4	tetrahedral	109.5^o	3	linear		HBr