Chapter 1: Structure and

Bondingmcmurry

Coverage:1. Electron Configurations.2. Lewis Structures3. Covalent and Ionic bonds4. Atomic and Molecular Orbitals5. Hybridization

• Goals:

Write the electron configuration for any element in the periodic table.

Write Lewis line bond structures for simple organic molecules.

Know how to calculate formal charges on atoms.

Know the definitions of a sigma and pi bonds.

Draw energy diagrams for formation of pi and sigma bonds.

Predict the number of sigma and pi bonds in a molecule.

Predict the hybridization of an atom in a molecule.

Predict the approximate bond angles in a molecule.

Hybridization of Atomic Orbitals

1. AOs on a single atom mix to form new, hybrid orbitals. These hybrid orbitals

have characteristics of both s and p orbitals.

2. Provides a means of explaining observed bond angles in organic molecules.

1-4

Methane

sp3

CH

H

HH

109.50

The carbon atom is sp3 hybridized to obtain tetrahedral geometry. All bond angles are equal at 109.50.

E

__ s

__ __ __ p

__

__ __ __ __ __ __ __sp3

Promote e- Mix orbitals

1-5

s + 3 p

=

4 sp3 orbitals

D:\rw32b2a.exe

1-6

Ethylene sp2 sp2

CH

HC

H

H116.6o

121.7o

The carbon atom is sp2 hybridized to obtain trigonal planar geometry

E

__ s

__ __ __ p

__

__ __ __ __ p __ __ __ sp2 hybrid

Promote e- Mix orbitals

1-7

s + 2 p

=

3 sp2 orbitals

sp2 Hybridization

There is one p orbital left over,and it would be along the z axis.

1-8

Orbital Picture of Ethylene

D:\rw32b2a.exe

1-9

Acetylene

C1

C2

HH

180o

spsp

E

__ s

__ __ __ p

__

__ __ __ __ __ p __ __ sp hybrid

promote e- Mix orbitals

D:\rw32b2a.exe

1-10

s + p = sp + sp

Two sp orbitals

Remember, there are two p orbitalsleftover and these would be locatedon the y and z axes.

y

z

xEach sp orbital possesses 50% s characterand 50% p character.

1-11

s + p = sp + sp

Two sp orbitals

Remember, there are two p orbitalsleftover and these would be locatedon the y and z axes.

y

z

xEach sp orbital possesses 50% s characterand 50% p character.

Orbital Picture of Acetylene

D:\rw32b2a.exe