Hybridization of Orbitals Sections 9.1 and 9.5 March 14, 2007

Tetrahedral Experimentally we know the bond angles (109.5º). But our current understanding of orbitals doesn’t allow us to achieve these bond angles.

sp3 Hybridization Molecules that have tetrahedral geometry like CH4, NH3, H2O, SO42-, and ClO3- exhibit sp3 hybridization on the central atom.

Methane with Hybridized Orbitals Overlap of the Hydrogen 1s orbitals with the hybridized sp3 orbitals from the central Carbon.

Trigonal Planar – sp2 Hybridization Molecules with trigonal planar geometry like SO3, C2H4, SeS2, CO32-, exhibit sp2 hybridization on the central atom.

Hybridized and Unhybridized Orbital View

Rotate 90 degrees

Bonding and hybridized orbitals Hybridized orbitals make sigma bonds Unhybridized orbitals make pi bonds http://www.dlt.ncssm.edu/TIGER/chem7.htm

Linear geometry - sp Hybridization Molecules that have a linear geometry like CO2, N2O, BeH2, HCN, C2H2 all exhibit sp hybrization on the central atom.

CO2 Structure

sp Hybridization

Pi bonds and Sigma Bonds CO2 exhibits sp hybridization on the C and sp2 hybridization on the Oxygens.

N2 Hybridization Diatomic Nitrogen has a Lewis structure showing a triple bond.

Hybridized Orbitals When Exceeding the Octet Rule

PCl5 dsp3 Hybridized Trigonal bipyramid geometry SeF4, PCl5, BrF3, XeCl2

Octahedral Geometry d2sp3 hybridization XeF4, BrCl5, SeI6

Delocalization of Electrons (9.5) In molecules that show resonance structures, we have a delocalization of electrons. The available unhybridized p orbitals all overlap and stabilize the structure through the π interactions. NO3-