1Welcome to CHM 1220/1225Please turn offcell phonespagesiPodsThank you!Today’s PlanAnnouncementsComplete Chapter 10•Pre-lecture Assignment 12 will be available at 2:00 p.m. today and is due by noon, Friday, October 5, 2007.•Chapter 10 Quiz is due by noon, Friday, October 5, 2007.•Chapter 10 Homework is due by 12:50 p.m. Friday, October 5, 2007Chapter 10Molecular Geometry and Chemical Bonding TheoryMolecular Geometry and Chemical Bonding TheoryMolecular Geometry and Directional Bonding1.The Valence-Shell Electron-Pair Repulsion (VSEPR) Model2.Dipole Moment and Molecular Geometry3.Valence Bond Theory4.Description of Multiple BondingMolecular Orbital Theory5.Principles of Molecular Orbital Theory6.Electron Configurations of Diatomic Molecules of the Second Period7.Molecular Orbitals and Delocalized Bonding
has intentionally blurred sections.
Sign up to view the full version.
2Valence bond theory is an approximate theory to explain the electron pair or covalent bond by quantum mechanics.A bond forms whenAn orbital on one atom comes to occupy a portion of the same region of space as an orbital on the other atom. The two orbitals are said to overlap.The total number of electrons in both orbitals is no more than two.The greater the orbital overlap, the stronger the bond.The greater the orbital overlap, the stronger the bond.Orbitals (except s-orbitals) bond in the direction in which they protrude or point, to obtain maximum overlap.Hybrid orbitals are orbitals used to describe the bonding that are obtained by taking combinations of atomic orbital of the isolated atoms.The number of hybrid orbitals formed always equals the number of atomic orbitals used.Hybrid orbitals are named by using the atomic orbitals that combined:one s-orbital + one p-orbital give two sp-orbitalsone s-orbital + two p-orbital give three sp2-orbitalsone s-orbital + three p-orbital give four sp3-orbitalsone s-orbital + three p-orbital + one d-orbital give five sp3d-orbitalsone s-orbital + three p-orbital + two d-orbital give six sp3d2-orbitalsHybrid orbitals have definite directional characteristics as described in the table below.