Chapter 1
Introduction and Review
Organic Chemistry,5th Edition
L,G,Wade,Jr.
Jo Blackburn
Richland College,Dallas,TX
Dallas County Community College District
2003,Prentice Hall
Chapter 1 2
Definitions
Old:,derived from living organisms”
New:,chemistry of carbon compounds”
From inorganic to organic,W?hler,1828
h e a t
N H 4
+
O C N
-
H 2 N C N H 2
O
u r e a=>
Chapter 1 3
Atomic Structure
protons,neutrons,and electrons
isotopes
C126 6 C14
=>
Chapter 1 4
Atomic Orbitals
2s orbital (spherical)
2p orbital =>
Chapter 1 5
Electronic Configurations
Aufbau principle,
Place electrons in
lowest energy
orbital first.
Hund’s rule,
Equal energy
orbitals are half-
filled,then filled.
=>
Chapter 1 6
Table 1-1
=>
Chapter 1 7
Bond Formation
Ionic bonding,electrons are transferred.
Covalent bonding,electron pair is shared,
=>
Chapter 1 8
Lewis Structures
Bonding electrons
Nonbonding electrons or lone pairs
Satisfy the octet rule! =>
C
H
H
H
O
H
Chapter 1 9
Multiple Bonding
=>
Chapter 1 10
Dipole Moment
Amount of electrical charge x bond length.
Charge separation shown by electrostatic
potential map (EPM).
Red indicates a partially negative region and
blue indicates a partially positive region.
C C
H
H H
H
=>
Chapter 1 11
Electronegativity and
Bond Polarity
Greater?EN means greater polarity
=>
Chapter 1 12
Calculating Formal Charge
For each atom in a valid Lewis
structure:
Count the number of valence electrons
Subtract all its nonbonding electrons
Subtract half of its bonding electrons
C
H
H
H
C
O
O P
O
OO
O
3 -
=>
Chapter 1 13
Ionic Structures
C
H
H
H N
H
H
H
+
C l
-
N a O C H 3 or O C H 3N a +
_X
=>
Chapter 1 14
Resonance
Only electrons can be moved (usually
lone pairs or pi electrons).
Nuclei positions and bond angles
remain the same.
The number of unpaired electrons
remains the same.
Resonance causes a delocalization of
electrical charge.
Example=>
Chapter 1 15
Resonance Example
The real structure is a resonance hybrid.
All the bond lengths are the same.
Each oxygen has a -1/3 electrical charge,
=>
N
O
OO
_ _
N
O
OO
_
N
O
OO
Chapter 1 16
Major Resonance Form
has as many octets as possible.
has as many bonds as possible.
has the negative charge on the most
electronegative atom.
has as little charge separation as
possible.
Example=>
Chapter 1 17
Major Contributor?
C
H
H
N
H
H
+
C
H
H
N
H
H
+
major minor,
carbon does
not have octet.
=>
Chapter 1 18
Chemical Formulas
Full structural formula
(no lone pairs shown)
Line-angle formula
Condensed structural
formula
Molecular formula
Empirical formula
CH3COOH
C2H4O2
CH2O
=>
C
H
H
H
C
O
O H
O H
O
Chapter 1 19
Calculating Empirical
Formulas
Given % composition for each element,
assume 100 grams.
Convert the grams of each element to
moles.
Divide by the smallest moles to get ratio.
Molecular formula may be a multiple of
the empirical formula.
=>
Chapter 1 20
Arrhenius Acids and Bases
Acids dissociate in water to give H3O+ ions.
Bases dissociate in water to give OH- ions.
Kw = [H3O+ ][OH- ] = 1.0 x 10-14 at 24° C
pH = -log [H3O+ ]
Strong acids and bases are 100%
dissociated.
=>
1 M1 M
C l
-
+H 3 O +H 2 O+H C l
Chapter 1 21
Br?nsted-Lowry
Acids and Bases
Acids can donate a proton.
Bases can accept a proton.
Conjugate acid-base pairs.
C H 3 C
O
O H + C H 3 N H 2 C H 3 C
O
O - + C H 3 N H 3 +
=>
acid base conjugate
base
conjugate
acid
Chapter 1 22
Acid and Base Strength
Acid dissociation constant,Ka
Base dissociation constant,Kb
For conjugate pairs,(Ka)(Kb) = Kw
Spontaneous acid-base reactions
proceed from stronger to weaker.
C H 3 C
O
O H + C H 3 N H 2 C H 3 C
O
O - + C H 3 N H 3 +
pKa 4.74 pKb 3.36 pKb 9.26 pKa 10.64
=>
Chapter 1 23
Determining Relative Acidity
Electronegativity
Size
Resonance stabilization of conjugate
base
=>
Chapter 1 24
Electronegativity
As the bond to H becomes more
polarized,H becomes more positive and
the bond is easier to break.
=>
Chapter 1 25
Size
As size increases,the H is more loosely
held and the bond is easier to break.
A larger size also stabilizes the anion.
=>
Chapter 1 26
Resonance
Delocalization of the negative charge on the
conjugate base will stabilize the anion,so the
substance is a stronger acid.
More resonance structures usually mean
greater stabilization.
C H 3 C H 2 O H < C H 3 C
O
O H < C H 3 S
O
O
O H
=>
Chapter 1 27
Lewis Acids and Bases
Acids accept electron pairs = electrophile
Bases donate electron pairs = nucleophile
C H 2 C H 2 + B F 3 B F 3 C H 2 C H 2 +_
nucleophile electrophile
=>
Chapter 1 28
End of Chapter 1
Introduction and Review
Organic Chemistry,5th Edition
L,G,Wade,Jr.
Jo Blackburn
Richland College,Dallas,TX
Dallas County Community College District
2003,Prentice Hall
Chapter 1 2
Definitions
Old:,derived from living organisms”
New:,chemistry of carbon compounds”
From inorganic to organic,W?hler,1828
h e a t
N H 4
+
O C N
-
H 2 N C N H 2
O
u r e a=>
Chapter 1 3
Atomic Structure
protons,neutrons,and electrons
isotopes
C126 6 C14
=>
Chapter 1 4
Atomic Orbitals
2s orbital (spherical)
2p orbital =>
Chapter 1 5
Electronic Configurations
Aufbau principle,
Place electrons in
lowest energy
orbital first.
Hund’s rule,
Equal energy
orbitals are half-
filled,then filled.
=>
Chapter 1 6
Table 1-1
=>
Chapter 1 7
Bond Formation
Ionic bonding,electrons are transferred.
Covalent bonding,electron pair is shared,
=>
Chapter 1 8
Lewis Structures
Bonding electrons
Nonbonding electrons or lone pairs
Satisfy the octet rule! =>
C
H
H
H
O
H
Chapter 1 9
Multiple Bonding
=>
Chapter 1 10
Dipole Moment
Amount of electrical charge x bond length.
Charge separation shown by electrostatic
potential map (EPM).
Red indicates a partially negative region and
blue indicates a partially positive region.
C C
H
H H
H
=>
Chapter 1 11
Electronegativity and
Bond Polarity
Greater?EN means greater polarity
=>
Chapter 1 12
Calculating Formal Charge
For each atom in a valid Lewis
structure:
Count the number of valence electrons
Subtract all its nonbonding electrons
Subtract half of its bonding electrons
C
H
H
H
C
O
O P
O
OO
O
3 -
=>
Chapter 1 13
Ionic Structures
C
H
H
H N
H
H
H
+
C l
-
N a O C H 3 or O C H 3N a +
_X
=>
Chapter 1 14
Resonance
Only electrons can be moved (usually
lone pairs or pi electrons).
Nuclei positions and bond angles
remain the same.
The number of unpaired electrons
remains the same.
Resonance causes a delocalization of
electrical charge.
Example=>
Chapter 1 15
Resonance Example
The real structure is a resonance hybrid.
All the bond lengths are the same.
Each oxygen has a -1/3 electrical charge,
=>
N
O
OO
_ _
N
O
OO
_
N
O
OO
Chapter 1 16
Major Resonance Form
has as many octets as possible.
has as many bonds as possible.
has the negative charge on the most
electronegative atom.
has as little charge separation as
possible.
Example=>
Chapter 1 17
Major Contributor?
C
H
H
N
H
H
+
C
H
H
N
H
H
+
major minor,
carbon does
not have octet.
=>
Chapter 1 18
Chemical Formulas
Full structural formula
(no lone pairs shown)
Line-angle formula
Condensed structural
formula
Molecular formula
Empirical formula
CH3COOH
C2H4O2
CH2O
=>
C
H
H
H
C
O
O H
O H
O
Chapter 1 19
Calculating Empirical
Formulas
Given % composition for each element,
assume 100 grams.
Convert the grams of each element to
moles.
Divide by the smallest moles to get ratio.
Molecular formula may be a multiple of
the empirical formula.
=>
Chapter 1 20
Arrhenius Acids and Bases
Acids dissociate in water to give H3O+ ions.
Bases dissociate in water to give OH- ions.
Kw = [H3O+ ][OH- ] = 1.0 x 10-14 at 24° C
pH = -log [H3O+ ]
Strong acids and bases are 100%
dissociated.
=>
1 M1 M
C l
-
+H 3 O +H 2 O+H C l
Chapter 1 21
Br?nsted-Lowry
Acids and Bases
Acids can donate a proton.
Bases can accept a proton.
Conjugate acid-base pairs.
C H 3 C
O
O H + C H 3 N H 2 C H 3 C
O
O - + C H 3 N H 3 +
=>
acid base conjugate
base
conjugate
acid
Chapter 1 22
Acid and Base Strength
Acid dissociation constant,Ka
Base dissociation constant,Kb
For conjugate pairs,(Ka)(Kb) = Kw
Spontaneous acid-base reactions
proceed from stronger to weaker.
C H 3 C
O
O H + C H 3 N H 2 C H 3 C
O
O - + C H 3 N H 3 +
pKa 4.74 pKb 3.36 pKb 9.26 pKa 10.64
=>
Chapter 1 23
Determining Relative Acidity
Electronegativity
Size
Resonance stabilization of conjugate
base
=>
Chapter 1 24
Electronegativity
As the bond to H becomes more
polarized,H becomes more positive and
the bond is easier to break.
=>
Chapter 1 25
Size
As size increases,the H is more loosely
held and the bond is easier to break.
A larger size also stabilizes the anion.
=>
Chapter 1 26
Resonance
Delocalization of the negative charge on the
conjugate base will stabilize the anion,so the
substance is a stronger acid.
More resonance structures usually mean
greater stabilization.
C H 3 C H 2 O H < C H 3 C
O
O H < C H 3 S
O
O
O H
=>
Chapter 1 27
Lewis Acids and Bases
Acids accept electron pairs = electrophile
Bases donate electron pairs = nucleophile
C H 2 C H 2 + B F 3 B F 3 C H 2 C H 2 +_
nucleophile electrophile
=>
Chapter 1 28
End of Chapter 1
