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Hybridization of atoms sall H atoms (shape is always linear) spany C with only 2 atoms attached (single and triple bond, two double bonds) (shape is linear) sp 2 any C with only 3 atoms attached (double bond) any N or O with a double bond (shape is trigonal planar or bent - 120 °) - PowerPoint PPT Presentation
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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