CHAPTER 11
Introduction to Organic Molecules &
Functional Groups
General, Organic, & Biological Chemistry
Janice Gorzynski Smith
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CHAPTER 11: Intro to Organic Molecules &
Functional Groups
Learning Objectives:
Difference between organic and inorganic molecules
Name characteristic features of organic compounds
Draw organic compounds, including skeletal structures
Identify common bond types, angles, and molecule
shapes
Name functional groups
Understand polarity and its effect on solubility and boiling
point
Explain the difference between fat and water soluble
vitamins
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
CHAPTER 11: Intro to Organic Molecules &
Functional Groups
Lecture Outline:
① Define Organic Chemistry
② Review the shape of organic molecules
③ How to Draw organic compounds
④ Overview of functional groups
⑤ Review intermolecular forces
⑥ Review polarity
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Organic
Chem
Definition
Organic Chemistry is the study of compounds containing
carbon.
o Both naturally occurring and synthetic compounds
o C, H, O, N, S, P, Halides (Cl, F, Br, I)
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
Brainstorm examples of organic and inorganic compounds.
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Organic
Chem
Definition
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Organic
Chem
Bonding
o Covalent Bond?
o Valence electron?
o Octet Rule?
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Organic
Chem
Bonding
A COVALENT BOND shares a pair of electrons between atoms.
o non-metal to non-metal bond
o The OCTET RULE states that atoms of main group elements make bonds
by gaining, losing, or sharing electrons to achieve an outer shell
containing 8 electrons.
How many valence electrons do
Carbon and Hydrogen have?
Oxygen?
Nitrogen?
Sulfur?
Phosphorous?
Chlorine?
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
How many bonds does each atom need to satisfy the octet rule?
C
H
O
N
S
P
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Group
Problem
Draw these molecules:
Ethane: C2H6
Cyclohexane: C6H12
Propene: C3H6
Propyne: C3H4
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Molecule
Shape
Bond Angle
VSEPR Theory: The most stable arrangement of
atoms in a molecule maximized the distance
between atoms and lone pairs.
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
Draw the lewis dot structures for water and ethanol.
How many lone pairs of electrons do they have?
What are the bond angles within the molecules?
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Group
Problem
Draw the lewis dot structure for ammonia. How
many lone pairs of electrons does it have?
What are the bond angles within the molecule?
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Molecule
Shape
Drawing Molecules
SIMPLIFY!
H
H
H
H
H
C
C
C
C
H
H
H
H
H
CH3CH2CH2CH3
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
Practice: 1) convert to condensed structure 2) simplify
further if possible 3) skeletal structure
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Functional
Groups
Overview
Hydrocarbon
Functional
Groups
Alkane
C−C
Alkene
C=C
Alkyne
C=C
Aromatic
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Functional
Groups
Overview
Alkyl
halides
Single Bond
to a
Heteroatom
Functional
Groups
Alcohols
Ethers
Amines
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Functional
Groups
Overview
Aldehydes
Carbonyl
Functional
Groups
Carboxylic
Acids
Esters
Ketones
Amides
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
Identify all of the functional groups
pentabromodiphenyl ether
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Group
Problem
Identify all of the functional groups
Estradiol
Genistein
A soy isoflavone
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Group
Problem
Identify all of the functional groups (other then alkanes)
in Gliadin C29H41N7O9
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Properties
of Organics
Overview
o Organic compounds experience weaker
intermolecular interactions because they
form covalent bonds.
o no ion-ion interactions
o Usually clear or yellowish color
o Often a liquid or a gas at room temperature
o Lower melting points and boiling
points relative to ionic compounds
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Properties
of Organics
Polarity
The difference in electronegativity between two
atoms bonded together creates a polar dipole
moment. The more electronegative atom has a
slight negative charge (more electron density).
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
What is the dipole moment of each bond, and what
is the overall dipole moment for each molecule?
Water
Acetone
Isopropanol
Acetic Acid
Diethyl Ether
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Properties
of Organics
Intermolecular Forces
Intermolecular Forces
weaker then intramolecular forces (bonding)
London Dispersion
Instantaneous dipole-induced attractions that
occur between all molecules, even non-polar.
Dipole-Dipole
Partial charges of polar compounds attract
each other .
Hydrogen Bonding
Strong dipole-dipole attraction when H is
covalently bonded to a highly electronegative
atom.
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Properties
of Organics
Intermolecular Forces
Intermolecular Forces
weaker then intramolecular forces (bonding)
London Dispersion
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Properties
of Organics
Intermolecular Forces
Intermolecular Forces
weaker then intramolecular forces (bonding)
Dipole-Dipole
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Properties
of Organics
Intermolecular Forces
Intermolecular Forces
weaker then intramolecular forces (bonding)
Hydrogen Bonding
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
Rank the three intermolecular forces discussed in
order of strength.
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Properties
of Organics
Solubility
LIKE DISSOLVES LIKE
polar molecules dissolve in polar solvents
nonpolar molecules dissolve in nonpolar solvents
Polar Solvents
Water: H2O
Methanol: CH3OH
Ethanol: CH3CH2OH
Acetone: (CH3)2CO
Acetic Acid: CH3CO2H
Ammonia: NH3
Acetonitrile: CH3CN
Nonpolar Solvents
Pentane: C5H12
Hexane: C6H14
Cyclohexane: C6H12
Benzene: C6H6
Toluene: CH3C6H5
Chloroform: CHCl3
Diethylether: (CH3CH2)2O
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Smith. General Organic & Biolocial Chemistry 2nd Ed.
Group
Problem
Draw all of the solvents from the previous slide and
prove they are polar or nonpolar.
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Properties
of Organics
Water & Fat Soluble Vitamins
Which type of solvent would the
following molecules dissolve in?
Vitamin A
Vitamin B12
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Molecules
BONDING: Lewis Bond Theory
strategy to tackle problems
NH3
1) Start with the least
electronegative element as the
central element
2) Surround the central element
with the bonding elements and
indicate their initial electrons
3) Add extra electrons, from
surrounding atoms, to the
central atom to satisfy the octet
rule
4) Use multiple bonds if necessary

H  N  H


H
 
H  N  H

H

H N H
H
Molecules
BONDING: Lewis Bond Theory
strategy to tackle problems
1) Initial electron bookkeeping:
2) Find the difference, this is the
number of electrons that must
be shared
NH3
H

 N  H

H
Need: 3x(1H x 2 e-) + (1N x 8 e-) = 14 eHave: 3x(1H x 1 e-) + (1N x 5 e-) = 8 e-
3) ÷ 2 to know the # of bonds
shared
(14 e-) – (8 e-) = 6 e(6 e-) ÷ 2 = 3 bonds
4) Arrange atoms around the most
electronegative element
5) Final electron bookkeeping:

H  N  H

H

H N H
H