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Warm-Up: to be turned in. Write the electron configuration, noble-gas configuration and orbital notation for: Sulfur and Calcium. VSPER Theory & Molecular Geometry. VSEPR Theory. stands for “valence-shell, electron-pair repulsion”
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Warm-Up: to be turned in Write the electron configuration, noble-gas configuration and orbital notation for: Sulfur and Calcium
VSEPR Theory • stands for “valence-shell, electron-pair repulsion” • When bonding occurs, the electrons pairs will orient themselves so they are spread out as far as possible • Refers to valence electrons of central atom in the molecule
VSEPR Molecular Geometry • Lewis Dot Structures can be used to predict molecular shape • Actual shape of the molecule is determined by the atoms only • Unpaired electrons on the central atom do take up space, however, and do affect the shape • Total number of electron concentrations= Shared pairs + lone pairs • Double and triple bonds are treated the same as single bonds, and have no affect on the molecular shape
Linear O C O • General formula: AB2 • 2 atoms bonded to central atom • Ex: CO2 180°
F F B F Trigonal Planar • General formula: AB3 • 3 atoms bonded to central atom • Ex: BF3 120°
Bent • 2 shared • 0 lone • Total: 3
Tetrahedral H H C H H • General formula: AB4 • 4 atoms bonded to central atom • Ex: CH4 109.5°
Trigonal Pyramidal H N H H • General formula: AB3 • 3 atoms bonded to central atom • 1 lone pair of electrons on central atom • Ex: NH3 107°
Bent O H H • General formula: AB2E or AB2E2 • 2 atoms bonded to central atom • 1 or 2 Lone pairs of electrons on central atom • Ex: H2O 105°
Homework: Due 10/26/2012 Draw Lewis Dot Structures for the following molecules. Then predict the molecular shape according to VSEPR theory. SCl2 PI3 Cl2O NH2Cl SiCl3Br