HYBRIDIZATION (9.1)

COVALENT BONDING:ORBITALS

HYBRIDIZATION (9.1)

HYBRIDIZATION

•Consider methane,CH4

•C has 4 valence electrons 1s2 2s2 2p2

•This suggests that there would be two kinds ofC-H bonds: one involving a 2s e- on carbonpairing with the 1s on H and the other involvinga 2p e- on carbon pairing with the 1s on H.

•Expt evidence confirms that the four C-H bondsin CH4 are identical and that CH4is tetrahedral.

Figure 9.1 a & b a) The LewisStructure of the Methane Moleculeb) The Tetrahedral MolecularGeometry of the Methane Molecule

HYBRIDIZATION (2)

•To resolve this conflict, promote a 2selectron to the empty 2p orbital, then mixor hybridize the 2s (1) and 2p (3) orbitalsto form four identical hybrid AOs namedsp3

•These hybrid atomic orbitals overlap withthe 1s orbital on hydrogen to form thecovalent C-H bond (sp3 – 1s).

•Hybrids form to minimize total energy.

HYBRIDIZATION (3)

•Using the VSEPR rules, C has fourcovalent bonds and has tetrahedralmolecular geometry. The H-C-H bondangle = 109.5o. This agrees with exptalmeasurements (4 identical C-H bonds).

•Hybridization integrates electronconfigurations with expt measurements.

•Other hybrids: sp2 (3 e pairs), sp (2),dsp3 (5), d2sp3 (6)

Figure 9.24Relationshipof theNumber ofEffectivePairs, TheirSpatialArrangement,and theHybrid OrbitalSet Required

Figure 9.8 The Hybridization of the s,px, and py Atomic Orbitals Results inthe Formation of Three sp2 OrbtitalsCentered in the xy Plane

Figure 9.9 An Orbital Energy-Level Diagram for sp2Hybridization

Figure 9.11 The Sigma Bondsin Ethylene

Figure 9.13 (a)The OrbitalsUsed to Form the Bonds inEthylene (b) The Lewis Structurefor Ethylene

Figure 9.16 The Orbital Energy-Level Diagram for the Formationof sp Hybrid Orbitals on Carbon

Figure 9.20 a-d (a) The sp hybridized N atom(b) The  bonds in the N2 molecule (c) The twopi bonds in N2 are formed when electron pairsare shared between two sets of parallel porbitals (d) The total bonding picture of N2