(
课件网) Chapter 7 Molecular Geometry and Bonding Theories Molecular Geometry and Bonding Theories 7 7.1 Molecular Geometry The VSEPR Model Electron-Domain Geometry and Molecular Geometry Deviation from Ideal Bond Angles Geometry of Molecules with More Than One Central Atom 7.2 Molecular Geometry and Polarity 7.3 Valence Bond Theory 7.4 Hybridization of Atomic Orbitals Hybridization of s and p Orbitals Hybridization of s, p, and d Orbitals 7.5 Hybridization of Molecules Containing Multiple Bonds 7.6 Molecular Orbital Theory Bonding and Antibonding Molecular Orbitals σ Molecular Orbitals Bond Order π Molecular Orbitals Molecular Orbital Diagrams 7.7 Bonding Theories and Descriptions of Molecules with Delocalized Bonding Molecular Geometry Molecular shape can be predicted by using the valence-shell electron-pair repulsion (VSEPR) model. A is the central atom surrounded by x B atoms. x can have integer values of 2 to 6. 7.1 ABx The VSEPR Model The basis of the VSEPR model is that electrons repel each other. Electrons are found in various domains. 2 double bonds 2 electron domains (on central atom) 1 single bond 1 double bond 1 lone pair 3 single bonds 1 lone pair 3 electron domains (on central atom) 4 electron domains (on central atom) Lone pairs Single bonds Double bonds Triple bonds Electron-Domain Geometry and Molecular Geometry The basis of the VSEPR model is that electrons repel each other. Electrons will arrange themselves to be as far apart as possible. Arrangements minimize repulsive interactions. 2 electron domains Linear 3 electron domains Trigonal planar Electron-Domain Geometry and Molecular Geometry 5 electron domains Trigonal bipyramidal 6 electron domains Octahedral 4 electron domains Tetrahedral Electron-Domain Geometry and Molecular Geometry The electron domain geometry is the arrangement of electron domains around the central atom. The molecular geometry is the arrangement of bonded atoms. In an ABx molecule, a bond angle is the angle between two adjacent A-B bonds. Trigonal bipyramidal Octahedral Tetrahedral Linear Trigonal planar 180° 120° 109.5° 90° 120° 90° Electron-Domain Geometry and Molecular Geometry AB5 molecules contain two different bond angles between adjacent bonds. Trigonal bipyramidal Axial positions; perpendicular to the trigonal plane Equatorial positions; three bonds arranged in a trigonal plane. 120° 90° Electron-Domain Geometry and Molecular Geometry When the central atom in an ABx molecule bears one or more lone pairs, the electron-domain geometry and the molecular geometry are no longer the same. O O O = Electron-Domain Geometry and Molecular Geometry Electron-Domain Geometry and Molecular Geometry Electron-Domain Geometry and Molecular Geometry The steps to determine the electron-domain and molecular geometries are as follows: Step 1: Draw the Lewis structure of the molecule or polyatomic ion. Step 2: Count the number of electron domains on the ... ...
