Hybridization of atoms

s all H atoms

(shape is always linear)

sp any C with only 2 atoms attached (single and triple bond, two double bonds)

(shape is linear)

sp2 any C with only 3 atoms attached (double bond)

any N or O with a double bond

(shape is trigonal planar or bent - 120°)

sp3 Any atom with all single bonds and a complete octet

(tetrahedral, trigonal pyramid, or bent – 109.5 °)

NH

H

O

O

H

O

O

N

H

H

Examples – Identify the hybridization, shape, and angles around each atom

1.

2.

Drawing Isomers• Determine the number of unsaturations (ring closures or

Π-bonds):– CnH2n+2 = saturated

– CnH2n = 1 unsaturation

– CnH2n-2 = 2 unsaturations

– For every 2 H lost, there is another unsaturation

• O does not count• F, Cl, Br, or I counts like an H• Every C has 4 bonds, N has 3, O has 2, H and X have 1.

Examples – Draw molecules (as many as possible) with the following formulas:

1. C8H12

2. C4H6O

Physical Properties of Organic Compounds• Homologous series – melting points and boiling points

increase with molecular size– CH4 < C2H6 < C3H8 < C4H10 …

• Melting Points and boiling points – depend on intermolecular forces:– Alkanes, alkenes and alkynes – nonpolar (LDF)

– Ethers and Halogenoalkanes – nearly nonpolar (LDF, slight dipole-dipole)

– Amides, tertiary amines, esters, aldehydes and ketones are polar (LDF and dipole-dipole)

– Alcohols, carboxylic acids, primary and secondary amines have LDF, dipole-dipole, and H-bonds. HIGHEST MP AND BP,

• Water solubility – depends on intermolecular forces:– More polar (especially if H-bonds), more soluble.

– Larger molecule (usually has a larger nonpolar part) becomes less soluble.

• Example – CH3OH > C2H5OH > C5H11OH …

• Soap – molecules with polar heads and nonpolar tails (allow nonpolar “dirt” to mix with water in micelles )

Solubility and Acid-Base Properties of Organic Substances

• Compounds with only C-C or C-H bonds are nonpolar and are soluble in nonpolar solvents and not very soluble in water.

• Water soluble organic molecules have polar functional groups.

• Surfactants have long nonpolar portions of the molecule with a small ionic or polar tip.

• The most important organic acids are carboxylic acids with the

-COOH functional group.

• Basic organic molecules are usually amines, -NH2, -NHR, or -NR2 functional groups.

• A molecule that exists as a pair of nonsuperimposable mirror images is called chiral. The two molecules are called stereoisomers or enantiomers.

• Organic compounds that contain one carbon atom that is attached to four different atoms or groups are chiral.

• Stereoisomers have the same structural formula but different arrangements of atoms in space.

Chirality in Organic Chirality in Organic ChemistryChemistry

• Consider *CHBr(CH3)(CH2CH2CH3). The *C is attached to: (i) H, (ii) Br, (iii) CH3, and (iv) CH2CH2CH3:

Chirality in Organic Chirality in Organic ChemistryChemistry

• Chiral molecules exist as a pair of enantiomers.• The enantiomers are nonsuperimposable mirror images.• Organic chemists label enantiomers as R and S.• If two enantiomers are placed in a solution in equal

amounts, then the mixture is called racemic.• If one molecule contains two stereogenic centers, one R

and one S, then the molecule shows no optical activity.• Many pharmaceuticals are chiral molecules.

Chirality in Organic Chirality in Organic ChemistryChemistry

S-ibuprofen:

O

OH

O

N

O

Circle any Chiral Carbons in the following molecules

Condensation Polymerization (ex – nylon, polyester)

• Produces H2O

R C

H

H

N

H

H OH

C

O

C

H

H

R' R C

H

H

N

H

C

O

C

H

H

R'

(poly) amideor polyester

amine(or alcohol)

acid

+ H2O