极性共价键，酸碱 chap2.pptVIP

在氢卤酸中，氢氯酸（盐酸）、氢溴酸和氢碘酸都是强酸，并且酸性按HCl-HBr-HI的顺序增强，只有氢氟酸是弱酸。氢卤酸酸性的变化可通过卤化氢在水溶液中解离过程各步顺序的焓变和熵变来说明。氢卤酸的酸性强弱主要与下列三个因素有关：一是负离子的水合热；二是X的电子亲合能：三是HX的键能。虽然F-的水合热很大，同时HF的键能又特别大，而氟的电子亲合能却比预期的小，致使它与其它氢卤酸不同，酸性显著的弱。 When atoms are similar in size, the stronger acid will have its proton attached to the more electronegative atom Inductive诱导的 electron withdrawal吸引 increases the acidity of a conjugate acid; Inductive effect: shifting of electrons in a bond in response to EN of nearby atoms Atoms either donate electrons (ie--Mg, Li) or withdraw e- (ie--O, Cl) Organic Acids: Effect (影响，效应)of Resonance on Acidity 共振对酸性的影响 For an alcohol, the anion is stabilized by having negative charge on a highly electronegative atom. For an acid, the anion is stabilized by having negative charge on a highly electronegative atom and by resonance. Two types of organic acids: O-H (Oxygen-Hydrogen Bond) ?O=C-C-H Organic Bases Have an atom with a lone pair of electrons that can bond to H+.（碱）有孤对电子，它们能与氢离子键合。 Nitrogen-containing compounds derived from ammonia are the most common organic bases. 由氨衍生的含氮化合物是最常见的有机碱。 Oxygen-containing compounds can react as bases when with a strong acid or as acids with strong bases. 含氧化合物遇到强酸时作为碱起反应，遇到强碱时作为酸起反应， p.57 2.11 Acids and Bases: The Lewis Definition Lewis acids are electron pair acceptors and Lewis bases are electron pair donors Lewis acid ---substance that accepts an electron pair.? Much broader definition and can include other species besides H+ Lewis base ---substance that donates an electron pair.? Donated pair of electrons is that shared between acid and base in a COVALENT bond.? Most oxygen nitrogen containing organic compounds are Lewis Bases because they have a lone pair of electrons. Br?nsted acids are not Lewis acids because they cannot accept an electron pair directly (only a proton would be a Lewis acid). Br?nsted酸不是Lewis酸，因为它们不能直接接受电子对。只有质子是Lewis酸。 The Lewis definition leads to a general description描述 of many reaction patterns模式