Wade英文原版有机化学课件—01

1、Chapter 1Introduction and ReviewOrganic Chemistry, 5th EditionL. G. Wade, Jr.Jo BlackburnRichland College, Dallas, TXDallas County Community College District 2003, Prentice Hall1DefinitionsOld: “derived from living organismsNew: “chemistry of carbon compoundsFrom inorganic to organic, Whler, 1828=2A

2、tomic Structureprotons, neutrons, and electronsisotopes=3Atomic Orbitals2s orbital (spherical)2p orbital =4Electronic ConfigurationsAufbau principle: Place electrons in lowest energy orbital first.Hunds rule: Equal energy orbitals are half-filled, then filled.=5Table 1-1=6Bond FormationIonic bonding

3、: electrons are transferred.Covalent bonding: electron pair is shared. =7Lewis StructuresBonding electronsNonbonding electrons or lone pairsSatisfy the octet rule! =8Multiple Bonding=9Dipole MomentAmount of electrical charge x bond length.Charge separation shown by electrostatic potential map (EPM).

4、Red indicates a partially negative region and blue indicates a partially positive region.=10Electronegativity and Bond PolarityGreater EN means greater polarity=11Calculating Formal ChargeFor each atom in a valid Lewis structure:Count the number of valence electronsSubtract all its nonbonding electr

5、onsSubtract half of its bonding electrons=12Ionic StructuresX=13ResonanceOnly electrons can be moved (usually lone pairs or pi electrons).Nuclei positions and bond angles remain the same.The number of unpaired electrons remains the same.Resonance causes a delocalization of electrical charge.Example=

6、14Resonance ExampleThe real structure is a resonance hybrid.All the bond lengths are the same.Each oxygen has a -1/3 electrical charge. =15Major Resonance Formhas as many octets as possible.has as many bonds as possible.has the negative charge on the most electronegative atom.has as little charge se

7、paration as possible.Example=16Major Contributor?majorminor, carbon doesnot have octet.=17Chemical FormulasFull structural formula (no lone pairs shown)Line-angle formulaCondensed structural formulaMolecular formulaEmpirical formulaCH3COOHC2H4O2CH2O =18Calculating Empirical FormulasGiven % compositi

8、on for each element, assume 100 grams.Convert the grams of each element to moles.Divide by the smallest moles to get ratio.Molecular formula may be a multiple of the empirical formula. =19Arrhenius Acids and BasesAcids dissociate in water to give H3O+ ions.Bases dissociate in water to give OH- ions.

9、Kw = H3O+ OH- = 1.0 x 10-14 at 24CpH = -log H3O+ Strong acids and bases are 100% dissociated.=20Brnsted-Lowry Acids and BasesAcids can donate a proton.Bases can accept a proton.Conjugate acid-base pairs.=acidbaseconjugatebaseconjugateacid21Acid and Base StrengthAcid dissociation constant, KaBase dis

10、sociation constant, KbFor conjugate pairs, (Ka)(Kb) = KwSpontaneous acid-base reactions proceed from stronger to weaker.pKa 4.74pKb 3.36pKb 9.26pKa 10.64=22Determining Relative AcidityElectronegativity Size Resonance stabilization of conjugate base =23ElectronegativityAs the bond to H becomes more p

11、olarized, H becomes more positive and the bond is easier to break.=24SizeAs size increases, the H is more loosely held and the bond is easier to break.A larger size also stabilizes the anion.=25ResonanceDelocalization of the negative charge on the conjugate base will stabilize the anion, so the substance is a stronger acid.More resonance structures usually me