1. Molecular Geometry and Bonding Theories Katherine Shin & Peedith Maldonado Chapter 9

2. Dedication Page Our lovely Chemistry teacher, Ms. Ramona Ricks = P.S- Give us an A  Please.

3. 9.1 Molecular Shapes • The overall shape of a molecule is determined by its bond angles, the angles made by the lines joining the nuclei of the atoms in the molecule. • The possible shapes of Abn molecules depend on the value of “n.” • Examples: AB2 molecule must be either linear or bent AB3 molecule must be either trigonal planar pr trigonal pyramidal

4. 9.2- The VSEPR Model • A bonding pair of electrons thus defines a region in which the electrons will more likely be found. (The region is referred to as electron domain) • Nonbonding pair (lone pair) of electrons defines an electron domain that is located principally on one atom. • THE VSEPR model is based on the idea that electron domains are negatively charged & therefore, repel each other. -The VSEPR predicts that the best arrangement of electron domains is the one that minimizes the repulsions among them.

5. Electron domain geometry- The arrangement Of electron domains about the central atom of a Molecule or ion. *Molecular geometry is the arrangement of only the atoms in a molecule or ion. • By looking at the VSEPR model, we can predict the electron-domain geometry. -From knowing how many domains are due to Nonbonding pairs, we can then predict the Molecular geometry of a molecule or ion from Its electron-domain geometry.

6. Electron domain geometries • There are five….

7. Molecular Geometry CO2 Linear 2 electron domains

8. Molecular Geometry Bent Trigonal Planar Trigonal Planar NO3 BF3 3 electron domains

9. Molecular Geometry Trigonal Pyramidal Tetrahedral NH3 CH4 Bent Tetrahedral 4 electron domains H2O

10. Molecular Geometry Seesaw Trigonal Bipyramidal SF4 PCl5 Trigonal Bipyramidal T-shaped 5 electron domains Linear ClF3 XeF2

11. Molecular Geometry Square Pyramidal Octahedral SF6 Octahedral 6 electron domains BrF5 Square Planar XeF4

12. 9.3 Molecular Shape & Molecular Polarity • For a molecule that consists of more than two atoms, the dipole moment depends on both the polarities of the individual bonds and the geometry of the molecule. O C O H Cl Polar Non-Polar

13. More Examples

14. 9.5 Hybrid Orbitals • Atomic orbitals on an atom mix to form new orbitals called hybrid orbitals. • The process of mixing atomic orbitals is called hybridization. • Provide a convenient model for using valence-bond theory to describe the covalent bonds in molecules with geometries that conform to the electron domain geometries predicted by the VSEPR model. • Steps that allow us to predict the hybrid orbitals used by an atom in the bonding: • Draw the lewis structure for the molecule or ion. • Determine the electron-domain geometry using the VSEPR model. • Specify the hybrid orbitals needed to accommodate the electron pairs based on their geometric arrangement. Example: NH3

16. QUIZ

17. Find: molecular formula, electron domain geometry, molecular geometry, number of electron domains(bonding/nonbonding), polarity, bond angles, hybridization Phosporushexaflouride (negative one ion) PF6

18. … P