Copyright©2000 by Houghton Mifflin Company. All rights reserved. 1 Covalent Bonding: Hybrid Atomic Orbitals

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  • Covalent Bonding: Hybrid Atomic Orbitals

    Copyright2000 by Houghton Mifflin Company. All rights reserved.

  • BondingWrite Lewis Structures.Determine the Arrangement of e- pairs using VSEPR Theory.Determine the hybrid atomic orbitals used to form bonds.

    Copyright2000 by Houghton Mifflin Company. All rights reserved.

  • HybridizationThe mixing of atomic orbitals to form special orbitals for bonding.The atoms are responding as needed to give the minimum energy for the molecule.

    Copyright2000 by Houghton Mifflin Company. All rights reserved.

  • Hybrid Orbitals

    Orbitals used to describe bonding that are obtained by taking combinations of atomic orbitals of the isolated atoms.

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  • Figure 9.1(a) Lewis Structure (b) Tetrahedral Molecular Geometry of the Methane Molecule

    By experiment, CH4 know to be tetrahedral with bond angles of 109.5.Experiments show 4 equivalent bonds.

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  • Valence electrons of carbon:

    2s2 2p2

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  • Figure 9.2The Valence Orbitals on a Free Carbon Atom: 2s, 2px, 2py, and 2pz Bonding assumed to involve only the valence electrons.

    Overlap with these orbitals would not give 109.5 bond angles.

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  • Hybridization A new set of atomic orbitals might better serve the C atom in forming molecules.

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  • Hybridization Hybridization = Modification of model to account for the observation.

    Atoms seem to use special orbitals when forming molecules.

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  • Figure 9.3The Formation of sp3 Hybrid Orbitalssp3 hybridization.

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  • Figure 9.5An Energy-Level Diagram Showing the Formation of Four sp3 OrbitalsFour equivalent carbon orbitals.

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  • Figure 9.6Tetrahedral Set of Four sp3 Orbitals

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  • Figure 9.7The Nitrogen Atom in Ammonia is sp3 Hybridized

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  • EthyleneH2C==CH2

    Each carbon atom is surrounded by three effective pairs.Requires a set of 3 orbitals with a trigonal planar geometry and 120 bond angles.

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  • Figure 9.8The Hybridization of the s, px, and py Atomic Orbitals

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  • Figure 9.9An Orbital Energy-Level Diagram for sp2 HybridizationOne 2p orbital of carbon is not used..

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  • Figure 9.10An sp2 Hybridized C Atom

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  • (sigma) bonds

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  • Figure 9.11The s Bonds in Ethylene

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  • Double BondDouble bond results from an additional bond----- a (pi) bond.

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  • Figure 9.12Sigma and Pi Bonding

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  • Figure 9.13The Orbitals for C2H4

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  • Whenever an atom is surrounded by3 effective e- pairs,

    a set of sp2 hybrid orbitals is required.

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  • A sigma () bond centers along the internuclear axis.A pi () bond occupies the space above and below the internuclear axis.Double Bonds

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  • CO2O==C==O

    2 effective pairs around central atom at an angle of 180

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  • Figure 9.14When One s Orbital and One p Orbital are Hybridized, a Set of Two sp Orbitals Oriented at 180 Degrees Results

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  • Figure 9.16The Orbital Energy-Level Diagram for the Formation of sp Hybrid Orbitals on CarbonA set of two sp orbitals.

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  • Figure 9.17The Orbitals of an sp Hybridized Carbon AtomTwo sp hybridizedorbitals.

    Two p unhybrizedOrbitals.

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  • Sigma Bonds

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  • Figure 9.19The Orbitals for CO2

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  • PCl55 e- pairs requires a geometry oftrigonal bipyramidal.

    Requires dsp3 hybridization.

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  • Figure 9.21A Set of dsp3 Hybrid Orbitals on a Phosphorus Atom

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  • Each Cl is surrounded by 4 e- pairs.

    They require sp3 hybridization.

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  • Figure 9.22(a) The Structure of the PCl5 Molecule (b) The Orbitals Used to Form the Bonds in PCl5

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  • SF66 e- pairs requires a geometry ofoctahedral.

    Requires d2sp3 hybridization.

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  • Figure 9.23An Octahedral Set of d2sp3 Orbitals on a Sulfur Atom

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  • The Localized Electron ModelDraw the Lewis structure(s)Determine the arrangement of electron pairs (VSEPR model).Specify the necessary hybrid orbitals.

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