Directions: Use the following outline provided for this chapter to build your knowledge and skills of content mastery needed for organic chemistry. (You can add to it in any that you would like or else create an entirely new/original chapter summary of your own design.)
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As you work on drafting your version of this chapter summary, remember to be thorough (and neat) and incorporate the following components in such a way that demonstrates your depth and breadth of knowledge of organic chemistry of the information covered in Chapter #1 – Structure and Bonding:
- Learning overviews, background information, and/or relevant introductions.
- Definitions of important vocabulary words and terminology to understand the context of the topics addressed in this stage of learning organic chemistry.
- Illustrations, diagrams, charts, figures, organic structures, chemical reactions, mechanisms, etc, to visualize how the processes of organic chemistry are developed to emphasize the key points of what you know.
- Examples of problems that you solve to reinforce what you are learning along with viable explanations of key aspects you mastered.
- An overall list of the top 8-10 most interesting/new things you learned from this particular chapter.
Page 1
C
H
APTER #1: STRUCTURE and B
O
NDING
ORGANIC CHEMISTRY
DEFINITIONS AND HISTORY
In the early 1800’s “organic molecules” came from an organism.
In 1828 Frederich Wohler synthesized urea (natural, organic) from ammonium cyanate (inorganic). Urea
had never before been made “…without thereby needing to have kidneys…”
Elements in Human Body Elements in Dry Human
Oxygen 65% Carbon 62%
Carbon 18% Nitrogen 11%
Hydrogen 10% Oxygen 9%
Nitrogen 3% Hydrogen 6%
Calcium 1.5% Calcium 5%
C NOH
N
H
H
H
C
O
N NH
H
H
H
heat
ammonium cyanate urea
Page 2
WHY CARBON?
ORGANIC CHEMISTRY TOPICS
Molecular Structure and Atomic Groupings
Ethyl alcohol (“alcohol”) Dimethyl ether (propellant)
Chemical Reactions
H C
H
H
C
H
H
O H H C
H
H
O C H
H
H
C
C
C
C
C
C C
O
O
O
H
H
H
H
H
H
C
C
C
C
C
C C
O
O
O
H
H
H
H
H C
O C
H
H
H
C
C
O
O
C
C
O
H
H
H
H
H
H
salicylic acid acetylsalicylic acid
Page 3
LEWIS STRUCTURES
METHO
D
1. Sum the valence electrons.
For each negative charge ____________________, for each positive charge ____________________.
2. Draw the skeleton (for complicated structures this may be given).
3. Use the valence electrons to give all atoms an octet (8 e–), except hydrogen which should have a duet
(2 e–).
EXAMPLES
CH2O (Formaldehyde) CH3NH–
CH2NH2– CH2NH2+
NaCN (sodium cyanide)
Page 4
FORMAL CHARGE
METHOD
For each element apply this formula:
Formal Charge = (Valence electrons) – (Electrons “owned” by the element)
HONC PRINCIPLE
When neutral… H makes
O makes
N makes
C makes
Anion Neutral Cation
HCONH– NO3–
+
H C
H
O H
H C
O
N H O N
O
O
Heme unit in hemoglobin
Page 5
RESONANCE STRUCTURES
REVIEW
CHO2–
Bond Lengths1
Labrador Poodle Carbonate bond lengths2
1 Allen, F.H., Kennard, O., J. Chem. Soc., Perkin Trans., 2, 1987, S1-S19 (follows p. 1914)
2 Solomons, G., Fryhle, C.B., Organic Chemistry, 8th ed., Wiley, 2004, pp. 15
H C
O
O
C
O
C
O
H C
O
O
O
C
O O
Page 6
RESONANCE
REASONABLE RESONANCE STRUCTURES
In “reasonable” resonance structures,
MAJOR AND MINOR CONTRIBUTORS
To follow are rules (in order of importance) for determining the major resonance contributor for a
compound:
1. A resonance structure where all atoms have an octet contributes more than a resonance structure that
lacks an octet (most important “rule”).
Electrostatic potential energy diagrams (color-coding electron density)3
3 Electrostatic potential energy diagrams in this chapter were generated by Lisa Nichols using WebMO, thanks to the Institute for
Chemical Literacy through Computational Science.
C O C O OC
O
C
HH
O
C
HH
C N
H
H H
H
H F
Page 7
2. A neutral resonance structure contributes more than one with charge, especially separated charge.
3. When all structures have octets and charge, the greatest contributor has the charge on the element
with the appropriate electronegativity.
a. A negative charge is best situated on the __________ electronegative atom.
b. A positive charge is best situated on the __________ electronegative atom.
H C
O
N
H
H
H C
O
N H
H C
O
N H
H
H
Page 8
MORE EXAMPLES
Draw all resonance structures, then rank in order from most important to least important to the overall
resonance hybrid. Explain your answer.
(There are 5 total, but only draw 2 more)
RESONANCE AND ENERGY
C
C
C
N
H
H
H
H
H
C
C
N
C
C
H
H
H
H
H C
O
O H C
O
O
H C
H
O
H
vs.
H C
O
O H C
O
O
H C
O
C H C
O
CH
H
H
H
vs.
Page 9
COMMON POLYATOMIC IONS
MOLECULAR SHAPE (VSEPR)
e– groups around
central atom
e– geometry
bond angles
central atom
hybridization
O
N
O
OO
N
O O
O
N
O
O
O
N
O O
N
O
O P
O
O
O
O
P O
O
O OP
O
O
O
O
PO
O
O
O
C
O
OO
C
O O
O
C
O
O
O Mn
O
O
O
O
Mn O
O
O OMn
O
O
O
O
MnO
O
O
Page 10
HYBRIDIZATION AND ORBITAL DIAGRAMS
VALENCE BOND THEORY
Bonding in F2
sp3 HYBRIDIZATION
Ammonia angles4
4 Jones, M., Fleming, S.A., Organic Chemistry, 4th ed., Norton, 2010, pp. 252
H N
H
H
orbital
diagram
H C
H
H
H
Page 11
sp2 HYBRIDIZATION
Ethylene angles5
sp HYBRIDIZATION
Total σ bonds: ________ π bonds: ________
5 Jones, M., Fleming, S.A., Organic Chemistry, 4th ed., Norton, 2010, pp. 46
O
C
H
C
H
H
H
H C
H
H
C C
C C
H
H H
H
Page 12
SHAPE AND HYBRIDIZATION SUMMARY
1. Assuming hybridization of the oxygen atom, lone pair A is in what type of orbital?
2. List the orbitals on both carbon atoms used to form the sigma bond labeled B.
3. Estimate bond angle C.
4. List the orbitals on carbon and oxygen atoms used to form the σ and π bond in D. σ:
π:
5. What is the electron geometry of the atom labeled E?
6. What is the hybridization of the nitrogen atom?
7. List the orbitals used to make the σ bond labeled F.
C C C
H
H
C
H
H
C
O
H
C
H
H
OH
N
O
A
B C
D
E
F
