1. Molecular Geometry VSEPR and beyond!

2. Molecular Geometry Three dimensional arrangment of atoms Molecular polarity determined by geometry and polarity of bonds Influences forces between molecules Two ideas explain and describe geometry: VVSEPR theory HHybridization

3. VSEPR Valence shell electron pair repulsion Repulsion between valence pairs causes them to be separated as far as possible Separation of electron pairs (and bonds) creates the geometry of the molecule

4. VSEPR: Steps Find the Lewis structure Analyze the structure:  A is central atom  B represents atoms bonded to A  E represents lone pairs on A Use Table 6-5 on page 186 to determine geometry

5. VSEPR Example Sample Problem 6-5 AlCl 3 Molecule is AB 3, so is trigonal-planar CBr 4 Molecule is AB 4, so is tetrahedral

6. VSEPR Example: Lone Pairs Only lone pairs on central atom matter! Sample Problem 6-6 Use VSEPR to predict the shape of a molecule of CO 2 AB 2, so is linear ClO 3 - AB 3 E, so is trigonal pyramidal