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 °)

Examples – Identify the hybridization, shape, and angles around each atom 1. 2.

Determine the number of unsaturations (ring closures or Π-bonds): 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.

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

Chirality in Organic Chemistry 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.

S-ibuprofen:

Circle any Chiral Carbons in the following molecules

Condensation Polymerization (ex – nylon, polyester) Produces H2O + H2O