Transcript Introduction to Bonding

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 ClO3exhibit 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 –
Hybridization
2
sp
• 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-