Structure and Bonding Molecular Orbital Theory Hybridization Isomerization Dipoles and Polarity

Structure and Bonding

Molecular Orbital Theory

Hybridization

Isomerization

Dipoles and Polarity

Orbitals are ProbabilitiesMotion of Electrons Described as Wave Functions

2s Orbital Has a Node

Bonding in H2

Sigma (Bond

Wave Depiction of H2 Waves reinforce

Molecular OrbitalsMathematical Combination of Atomic Orbitals

Antibonding Molecular Orbital Destructive Overlap Creates Node

and * of H2Each Wave Function Corresponds to a

Different Energy State for an Electron

Energy Released When Bond Forms

The p Orbital

px, py, pz

Ground State Electron Configurations

Electron Configuration of Carbon

Lewis Dot Structure of Methane

C...

.

carbon - 4 valence e hydrogen - 1 valence e

H.

1s22s22p2 1s

Tetrahderal Geometry

Methane Representations

In Ground State2 bonding sites, 1 lone pair

ground state

zyx2p

2sH

HH

H

CCH4

sp3 Hybridization 4 Regions of electron Density link

4

tetrahedral geometryexcited state

hybridize

4 identical sp3 orbitalszyx2p

2s4 sigma bonds requires 4 hybrid orbitals

CH4C

H

HH

H 2s

2p x y z

ground state

sp3

Hybridization of 1 s and 3 p Orbitals – sp3

sp3 is Tetrahedral GeometryMethane

Ammonia Tetrahedral Geometry

Pyramidal Shape

All Have the Same GeometryAll Have 4 Regions of Electron Density

Orbital Depiction of Ethane, C2H6 , the bond

Bonding Characteristics of Period 2 Elements

A Saturated Hydrocarbon

sp2 Hybridization3 Regions of Electron Density

pz

H

HC

H

H

CH2=CH2

C

3 sigma bonds requires 3 hybrid orbitals

2s

2p x y z

ground state

2s

2p x y z3 identical sp2 orbitals

hybridize

excited statetrigonal planar geometry

3sp2 pz

Hybridization of 1 s and 2 p Orbitals – sp2

An sp2 Hybridized Atom

Ethylene CH2=CH2

Views of Ethylene, C2H4

Ethylene

Formaldehyde

sp Hybridization2 Regions of Electron Density

py

H C HC

pz

2 sigma bonds requires 2 hybrid orbitals

2s

2p x y z

ground state

2s

2p x y z2 identical sp orbitals

hybridize

excited statelinear geometry

2

The sp Orbital

Acetylene, C2H2, 1 bond

2 perpendicular bonds

Pauling Electronegativity Scale

Electrostatic Potential Map Cholormethane

Opposite polarity in CH3Li

Methanol

Dipole Moment () is sum of the Bond Moments

Nonpolar CompoundsBond Moments Cancel Out

Dipole Moment reflects Both Resonance Structures

C N

O

O

H

H

HHH

H

N

O

O

C

Resonance Hybrid

C

H

HH

O

O

N

NCl3 and BCl3

NClCl

Cl B

Cl

= 0

Cl Cl

N-Cl bond momentsdo not cancel N

sp3 sp2

pyramidal trigonal planar

Dipole Moments

Dipole-Dipole Interactions

London Dispersion Forces

The Effect of Branching on Boiling Point

Polar Solute in H2O

Polar Solute in Nonpolar Solvent

Nonpolar Solute in Nonpolar Solvent

Hydrogen Bonding