Part IlI Symmetry and BondingChapter 1 Symmetry and Point Groups第一章对称性与点群Prof.Dr.XinLu（吕鑫）Email: xinlu@xmu.edu.cnhttp://pcoss.xmu.edu.cn/xlv/index.htmlhttp://pcoss.xmu.edu.cn/xlv/courses/theochem/index.html
Part III Symmetry and Bonding Prof. Dr. Xin Lu (吕鑫) Email: xinlu@xmu.edu.cn http://pcoss.xmu.edu.cn/xlv/index.html http://pcoss.xmu.edu.cn/xlv/courses/theochem/index.html Chapter 1 Symmetry and Point Groups 第一章 对称性与点群
Recommended books.Vincent A.,Molecular Symmetry and Group Theory,2nd edition,Wiley,2001·Barrett J., Structure andBonding,RSC, 2001· Cotton F. A., Chemical Applications of Group Theory, 3rd edition, Wiley, 1990.: Atkins P. W. & Friedman R. S., Molecular Quantum Mechanics, 4th edition, OUP, 2005Physical Chemistry,Donald A McOuarrie and John D. SimonUniversityScienceBooksGood for otherparts of the coursetoo
Recommended books • Vincent A., Molecular Symmetry and Group Theory, 2nd edition, Wiley, 2001. • Barrett J., Structure and Bonding, RSC, 2001 • Cotton F. A., Chemical Applications of Group Theory, 3rd edition, Wiley, 1990. • Atkins P. W. & Friedman R. S., Molecular Quantum Mechanics, 4th edition, OUP, 2005 • Physical Chemistry, Donald A McQuarrie and John D. Simon University Science Books Good for other parts of the course too
1.1 Introduction. In this course we will explore how the symmetry of molecules can be described preciselyusing Group Theory and how, armed with the concepts from this theory, we can go on topredict andunderstand importantpropertiesofmolecules. In particular we shall focus on02p1bi)how symmetry helps us to construct molecular orbitalLAH1sdiagrams;ii)howithelpsinthecalculationoftheenergiesand02spreciseform ofthe orbitalsii) how to use symmetry to predict and describe thehydrogenoxygenproperties of the vibrational normal modes ofAOsAOs/SOsMOsmolecules and theiractivityinIR andRaman spectraMolecular orbital diagramforH,O
1.1 Introduction • In this course we will explore how the symmetry of molecules can be described precisely using Group Theory and how, armed with the concepts from this theory, we can go on to predict and understand important properties of molecules. • In particular we shall focus on i) how symmetry helps us to construct molecular orbital diagrams; ii) how it helps in the calculation of the energies and precise form of the orbitals. iii) how to use symmetry to predict and describe the properties of the vibrational normal modes of molecules and their activity in IR and Raman spectra. Molecular orbital diagram for H2O H 1s O 2p O 2s
1.1.1 The SimplePowerfulness of Symmetry. The symmetry possessed by a molecule has a powerful influence on its properties.? For example, benzene ~high symmetry!>All of the carbon atoms are equivalent, thus havingHHthesameproperties,suchaschemicalshift>Likewise,theelectrondensityoneachhydrogen isHHthe same.> If a calculation predicted that this was not so, weHHwouldimmediatelyknowthatthecalculationmustbewrong
1.1.1 The Simple Powerfulness of Symmetry • The symmetry possessed by a molecule has a powerful influence on its properties. • For example, benzene ~ high symmetry！ All of the carbon atoms are equivalent, thus having the same properties, such as chemical shift. Likewise, the electron density on each hydrogen is the same. If a calculation predicted that this was not so, we would immediately know that the calculation must be wrong
1.1.2分子形状与对称性简介“更对称”？对称与视觉美感对称物体-由完全等同部件组成球形立方体>对称之美--日常生活中随处可见NH3H20分子对称性一因原子几何排列而具有一定的外形和对称性，可根据对称性特征对分子进行分类正四面体型：CH4vsSO42三角锥型：NH3VsSO3
1.1.2 分子形状与对称性简介 对称与视觉美感 对称之美 - 日常生活中随处可见 对称物体 - 由完全等同部件组成 分子对称性 – 因原子几何排列而具有一定的外形和对称性，可根据对称性特征对分子进行分类； “更对称”- ？ 球形 ? 立方体 NH3 ? H2O > > 正四面体型：CH4 vs SO4 2– 三角锥型：NH3 vs SO3 2–