Chemistry
Name:
§ 16.05 Bonding: Molecular Geometry: VSEPR
Most Important Idea:
Background
The geometry of a molecule is useful in predicting their properties. For example, polar
molecules dissolve polar particles (‘like dissolves like’); nonpolar molecules do not dissolve in
polar substances. For example: oxygen in water; oil in water; ammonium (NH4+) in water.
In a polyatomic molecule, the geometry of a molecule is determined by separating electrons as
far apart as possible. (Reduces repulsion between electrons.) The method used to determine the
molecular geometry is call the Valence-shell electron-pair repulsion (VSEPR) model. An atom
bonded to the central atom has some attraction to nearby electrons because the atom has a
positive nucleus. Nonbonding (lone pair) electrons only repel other electrons because they do
not have a nucleus to attract nearby electrons.
Model
Water
H2O
AB2E2
Problems
Determine the molecular geometries for each of the following molecules. Write the formula,
draw the Lewis structure, determine the VSEPR model (e.g., AB2, AB4), and draw the angles
between the bonded atoms.
1. H2
5. CH3OCH3
BF3
2. SO2
6. HCN
3. SO2Cl2
7. SF4 (see below)
SF4
F:\2014-2015\330_ModChem\330_sections\330_06_Bonding\06.05a.VSEPR.docx
4. H3COH
8. BF3 (see below)
Chemistry
VSEPR
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