Chem. Chem. 212 212 Molecular Molecular Structures Structures

Chem. Chem. 212 212 Molecular Molecular Structures Structures and Geometries and Geometries Hand in to TA: VSEPR-Pre-lab; Solubility Report, GCFs. Pick up one Model Kit per group. Hybridization of carbon Follow Sequence of: Lewis -> AXE -> VSEPR Follow format (see later slide) methane ethane vs. ethene vs. ethyne Lab report due next week: (Tue-Group next Tue 9:30 am); (Wed-Group next Wed 2:00 pm); (Fri-Group next Thu 12:00 nn). CyberChem (VSEPR) video Hybridization Hybridization of of Carbon Carbon Free Carbon E Bonding in Carbon 2p 2s Four Equivalent sp3 Hybridized Orbitals (Tetrahedral) Methane Ethane versus Ethene (Geometrical Isomers)

Ethyne Bromochloroiodomethane (Stereoisomers) Drawing Lewis Structures 1. 2. 3. 4. 5. 6. Follow Step by Step Method (See Ng Web-site) Total all valence electrons. [Consider Charge] Write symbols for the atoms and guess skeleton structure [ define a central atom ]. Place a pair of electrons in each bond. Complete octets of surrounding atoms. [ H = 2 only ] Place leftover electrons in pairs on the central atom. If there are not enough electrons to give the central atom an octet, look for multiple bonds by transferring electrons until each atom has eight electrons around it. CyberChem video HyperChem Summary Summary of of VSEPR VSEPR Molecular Molecular Shapes Shapes e-pairs Notation Name of VSEPR shape Examples

2 AX2 Linear HgCl2 , ZnI2 , CS2 , CO2 3 AX3 Trigonal planar BF3 , GaI3 AX2E Non-linear (Bent) SO2 , SnCl2 AX4 Tetrahedral CCl4 , CH4 , BF4- AX3E (Trigonal) Pyramidal NH3 , OH3- AX2E2 Non-Linear (Bent)

H2O , SeCl2 AX5 Trigonal bipyramidal PCl5 , PF5 AX4E Distorted tetrahedral (see-sawed) TeCl4 , SF4 AX3E2 T-Shaped ClF3 , BrF3 AX2E3 Linear I3- , ICl2- AX6 Octahedral SF6 , PF6- AX5E Square Pyramidal IF5 , BrF5

CyberChem Square Planar ICl4- , BrF See 4 Ng Web-site 4 5 6 HyperChem AX4E2 video Lewis/AXE/VSEPR Lewis/AXE/VSEPRFormat Format Formula/Name (Total # valence e-) PF3 phosphorus trifluoride (26) Lewis Structure and AXE Notation VSEPR 3D Drawing Name of Shape of all possible central atoms