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CHAPTER 11Introduction to Organic Molecules &

Functional Groups

General, Organic, & Biological ChemistryJanice Gorzynski Smith

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CHAPTER 11: Intro to Organic Molecules & Functional Groups

Smith. General Organic & Biolocial Chemistry 2nd Ed.

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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CHAPTER 11: Intro to Organic Molecules & Functional Groups

Smith. General Organic & Biolocial Chemistry 2nd Ed.

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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Organic Chem Definition

Smith. General Organic & Biolocial Chemistry 2nd Ed.

Organic Chemistry is the study of compounds containing carbon.

o Both naturally occurring and synthetic compoundso C, H, O, N, S, P, Halides (Cl, F, Br, I)

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GroupProblem

Brainstorm examples of organic and inorganic compounds.

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Organic Chem Definition

Smith. General Organic & Biolocial Chemistry 2nd Ed.

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Organic Chem Bonding

Smith. General Organic & Biolocial Chemistry 2nd Ed.

o Covalent Bond?

o Valence electron?

o Octet Rule?

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Organic Chem Bonding

Smith. General Organic & Biolocial Chemistry 2nd Ed.

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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GroupProblem

How many bonds does each atom need to satisfy the octet rule?

C

H

O

N

S

P

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GroupProblem

Draw these molecules:

Ethane: C2H6

Cyclohexane: C6H12

Propene: C3H6

Propyne: C3H4

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Molecule Shape Bond Angle

Smith. General Organic & Biolocial Chemistry 2nd Ed.

VSEPR Theory: The most stable arrangement of atoms in a molecule maximized the distance between atoms and lone pairs.

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GroupProblem

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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GroupProblem

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

Smith. General Organic & Biolocial Chemistry 2nd Ed.

SIMPLIFY!

C CCCH HHH

H HHH HH

CH3CH2CH2CH3

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GroupProblem

Practice: 1) convert to condensed structure 2) simplify further if possible 3) skeletal structure

Functional Groups Overview

16Smith. General Organic & Biolocial Chemistry 2nd Ed.

Alkane

Alkene

Alkyne

Aromatic

C − C

C = C

C = C

HydrocarbonFunctional

Groups

Functional Groups Overview

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Alkyl halides

Alcohols

Ethers

Amines

Single Bondto a

HeteroatomFunctional

Groups

Functional Groups Overview

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Aldehydes

Carboxylic Acids

Esters

Ketones

Amides

CarbonylFunctional

Groups

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GroupProblem

Identify all of the functional groups

pentabromodiphenyl ether

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GroupProblem

Identify all of the functional groups

Estradiol GenisteinA soy isoflavone

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GroupProblem

Identify all of the functional groups (other then alkanes) in Gliadin C29H41N7O9

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Properties of Organics Overview

Smith. General Organic & Biolocial Chemistry 2nd Ed.

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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Properties of Organics Polarity

Smith. General Organic & Biolocial Chemistry 2nd Ed.

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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GroupProblem

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

Smith. General Organic & Biolocial Chemistry 2nd Ed.

Intermolecular Forcesweaker then intramolecular forces (bonding)

London Dispersion

Dipole-Dipole

Hydrogen Bonding

Instantaneous dipole-induced attractions that occur between all molecules, even non-polar.

Partial charges of polar compounds attract each other .

Strong dipole-dipole attraction when H is covalently bonded to a highly electronegative atom.

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Properties of Organics Intermolecular Forces

Smith. General Organic & Biolocial Chemistry 2nd Ed.

Intermolecular Forcesweaker then intramolecular forces (bonding)

London Dispersion

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Properties of Organics Intermolecular Forces

Smith. General Organic & Biolocial Chemistry 2nd Ed.

Intermolecular Forcesweaker then intramolecular forces (bonding)

Dipole-Dipole

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Properties of Organics Intermolecular Forces

Smith. General Organic & Biolocial Chemistry 2nd Ed.

Intermolecular Forcesweaker then intramolecular forces (bonding)

Hydrogen Bonding

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GroupProblem

Rank the three intermolecular forces discussed in order of strength.

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Properties of Organics Solubility

Smith. General Organic & Biolocial Chemistry 2nd Ed.

LIKE DISSOLVES LIKEpolar molecules dissolve in polar solvents

nonpolar molecules dissolve in nonpolar solvents

Polar SolventsWater: H2OMethanol: CH3OHEthanol: CH3CH2OHAcetone: (CH3)2COAcetic Acid: CH3CO2HAmmonia: NH3

Acetonitrile: CH3CN

Nonpolar SolventsPentane: C5H12

Hexane: C6H14

Cyclohexane: C6H12

Benzene: C6H6

Toluene: CH3C6H5 Chloroform: CHCl3Diethylether: (CH3CH2)2O

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GroupProblem

Draw all of the solvents from the previous slide and prove they are polar or nonpolar.

Properties of Organics Water & Fat Soluble Vitamins

Smith. General Organic & Biolocial Chemistry 2nd Ed.

Which type of solvent would the following molecules dissolve in?

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Vitamin A

Vitamin B12

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Molecules BONDING: Lewis Bond Theory strategy to tackle problems

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

NH H

H

NH3

NH H

H

NH 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

3) ÷ 2 to know the # of bonds shared

4) Arrange atoms around the most electronegative element

5) Final electron bookkeeping:

NH

NH3

H

H

Need: 3x(1H x 2 e-) + (1N x 8 e-) = 14 e-

Have: 3x(1H x 1 e-) + (1N x 5 e-) = 8 e-

(14 e-) – (8 e-) = 6 e-

(6 e-) ÷ 2 = 3 bonds

NH H

H

NH H

H