厦门大学化学化工学院：《有机化学》课程教学资源（课件讲稿，双语版）第一章 碳的化合物与化学键 Carbon Compounds and Chemical Bonds（1.3）有机化学的结构理论 The Structural Theory of Organic Chemistry

ORGANIC CHEMISTRY Chapter l 1. 3 The Structural Theory of Organic chemistry Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 1.3 The Structural Theory of Organic Chemistry

ORGANIC CHEMISTRY Chapter I o 1858-1861, Kekule, Couper, and Butlerov laid the basis for one of the most fundamental theories in chemistry: the structural theory Valence(化合价):C- tetravalent;O divalent:H-monovalent 9 A carbon atom can use one or more of its valences to form bonds to other carbon atoms C-C C-C C≡C ingle bone Double bond Triple bond o Organic chemistry: a study of the compounds of carbon. (Kekule) Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 1858 ~ 1861, Kekulé, Couper, and Butlerov, laid the basis for one of the most fundamental theories in chemistry: the structural theory. Valence（化合价）: C — tetravalent; O — divalent; H — monovalent. A carbon atom can use one or more of its valences to form bonds to other carbon atoms. C C C C C C Single bond Double bond Triple bond Organic chemistry: a study of the compounds of carbon. (Kekulé)

ORGANIC CHEMISTRY Chapter l 1.3 A somers(异构体): The importance of Structural formulas ● Isomerism(异构现象) o Isomers: different compounds that have the same molecular formula Isomeric(同分异构) g Structural formulas(结构式) ● Constitutional isomers(构造异构体): different compounds that have the same molecular formula but differ in their connectivity, that is, in the sequence in which their atoms are bonded together Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 1.3A Isomers（异构体）: The importance of Structural Formulas Isomerism（异构现象） Isomers: different compounds that have the same molecular formula. Isomeric（同分异构） Structural formulas（结构式） Constitutional isomers（构造异构体）: different compounds that have the same molecular formula, but differ in their connectivity, that is, in the sequence in which their atoms are bonded together

ORGANIC CHEMISTRY Chapter l 9 1.3B The Tetrahedral shape of methane 10928 H… Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 1.3B The Tetrahedral Shape of Methane

ORGANIC CHEMISTRY Chapter l o 1.4 Chemical Bonds: The octet Rule(八偶规则) o lonic Bonds o Covalent Bonds o 1.5 Writing Lewis Structures o 1.6 Exceptions to the Octet Rule °17 Formal charge(形式电荷) Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 1.4 Chemical Bonds: The Octet Rule（八偶规则） Ionic Bonds Covalent Bonds 1.5 Writing Lewis Structures 1.6 Exceptions to the Octet Rule 1.7 Formal Charge（形式电荷）

ORGANIC CHEMISTRY Chapter l 1.8 Resonance 共振 Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 1.8 Resonance 共振

ORGANIC CHEMISTRY Chapter l More than one equivalent lewis structure can be written for many molecules and ions. For example O :O: 0: O O 2 Resonance structures(共振结构式) Notice two important features of these structures 1. Each atom has the noble gas configuration 2. We can convert one structure into any other by changing only the positions of the electrons. we do not need to change the relative positions of the atomic nuclei Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 More than one equivalent Lewis structure can be written for many molecules and ions. For example: O C O O O C O O O C O O 1 2 3 Resonance structures（共振结构式） Notice two important features of these structures: 1. Each atom has the noble gas configuration. 2. We can convert one structure into any other by changing only the positions of the electrons. We do not need to change the relative positions of the atomic nuclei

ORGANIC CHEMISTRY Chapter l Resonance Theory(共振论) e This theory states that whenever a molecule or ion can be represented by two or more Lewis structures that differ only in the positions of the electrons o two things will be true None of these structures which we call resonance structure or resonance contributors will be a correct representation for the molecules or ion. None will be in complete accord with the physical or chemical properties of the te substance g The actual molecule or ion will be better represented by a hybrid of these structures Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 Resonance Theory（共振论） This theory states that whenever a molecule or ion can be represented by two or more Lewis structures that differ only in the positions of the electrons. Two things will be true None of these structures ,which we call resonance structure or resonance contributors, will be a correct representation for the molecules or ion. None will be in complete accord with the physical or chemical properties of the substance. The actual molecule or ion will be better represented by a hybrid of these structures

ORGANIC CHEMISTRY Chapter l Resonance structures, then, are not structures for the actual molecule or ion they exist only in theory. CH2-CH=O CH,-CH-O CH2=CH-CH2 CH2CH=CH2 ++CH2-CH-CH2 2 3 CH2--CH-CH CH2-CH-CH 2 2 5 Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 Resonance structures, then, are not structures for the actual molecule or ion; they exist only in theory. Resonance structures, then, are not structures for the actual molecule or ion; they exist only in theory. CH2 CH O CH2 CH O CH2 CH CH2 CH2 CH CH2 CH2 CH CH2 CH2 CH CH2 CH2 CH CH2 1 2 3 4 5

ORGANIC CHEMISTRY Chapter l 1.9 Quantum Mechanics 1.10 Atomic Orbitals 1.11 Molecular orbitals Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 1 1.9 Quantum Mechanics 1.10 Atomic Orbitals 1.11 Molecular Orbitals