中国海洋大学：《无机化学 Concise Inorganic Chemistry》课程教学资源（PPT课件，英文）Chapter 9 Chemical Bonds and Molecular Structures

Chapter 9 Chemical Bonding andMolecular Structure

1 Chapter 9 Chemical Bonding and Molecular Structure

What is chemical bonding?Chemical bonds refer to the main, direct, andstrong forces between atoms and ionsWhat chemical bonds types are there?covalentbondsionic bondsmetal bonds

2 What is chemical bonding? Chemical bonds refer to the main, direct, and strong forces between atoms and ions. What chemical bonds types are there? • covalent bonds • ionic bonds • metal bonds

Three objectives:Covalent bonding and atomic crystalslonic bonds andionic substancesIntermolecularforcesandmolecularcrystals

3 Three objectives: ◼ Covalent bonding and atomic crystals ◼ Ionic bonds and ionic substances ◼ Intermolecular forces and molecular crystals

9-1 Covalent bondingand atomic crystals9-1-1 Valence bonding theory9-1-2Hybridization9-1-3Valenceshell electronpairrepulsion(VSEPR)9-1-4 Molecular Orbit Theory

4 9-1 Covalent bonding and atomic crystals 9-1-1 Valence bonding theory 9-1-2 Hybridization 9-1-3 Valence shell electron pair repulsion （VSEPR） 9-1-4 Molecular Orbit Theory

Ouestion1:How do molecules form from atoms ofelements withthesameor closeelectronegativity?Why the hydrogen molecule exists as H,instead of H3 or any other molecularformula?

5 Question 1: How do molecules form from atoms of elements with the same or close electronegativity? Why the hydrogen molecule exists as H2 instead of H3 or any other molecular formula?

9-1-1 Valence bonding theory1916年，路易斯提出经典共价键理论；1927年，海特勒-伦敦等用量子力学处理氢分子结构A/EAEs↑↑0↑R/pmRo=87pmFigure9-1RelationshipbetweenHenergyanditsnucleusdistance.6

6 9-1-1 Valence bonding theory 0 E/eV R0=87pm R/pm Es EA Figure 9-1 Relationship between H2 energy and its nucleus distance. 1916年, 路易斯提出经典共价键理论; 1927年, 海特勒-伦敦等用量子力学处理氢分子结构

xPx-spx(b)(c)(a)Figure9-2SchematicsofHCIbondingThe bonding atomic orbitals must overlap as muchaspossible,thatis,they must overlapinthemaximumwavefunctiondirection

7 - + + z x px-s (a) - + + z x px (b) s - + + z x px (c) s Figure 9-2 Schematics of HCl bonding. The bonding atomic orbitals must overlap as much as possible, that is, they must overlap in the maximum wave function direction

价键理论（VB法）·具有自旋方向相反的单电子的原子相互接近时，单电子可以配对构成共价键重叠越多，形成的共价键越稳定，即原子轨道最大重叠原理X

8 价键理论(VB法) • 具有自旋方向相反的单电子的原子相互 接近时,单电子可以配对构成共价键. • 重叠越多，形成的共价键越稳定，即原 子轨道最大重叠原理

共价键的特征1.具有饱和性（所形成的共价键数目取决于它所具有的未成对电子数2.具有方向性（形成共价键时，原子间总是尽可能沿着原子轨道最大重叠的方向成键

9 共价键的特征 1. 具有饱和性（所形成的共价键数目取决于 它所具有的未成对电子数） 2. 具有方向性（形成共价键时，原子间总是 尽可能沿着原子轨道最大重叠的方向成键）

two types of covalent bonds键型-sigma(o) bonds and pi(π) bonds键，元键The line through the two nucleus is calledinternuclear axis( bond axes键轴) x.sigma symmetrical orbital, such as ys,px,dx2-y2,Vdz2,pi symmetrical orbital, such as Vpy, Vpz,Vdxy, dyz, dxz10

10 two types of covalent bonds键型— sigma(σ) bonds and pi() bonds σ键，π键 The line through the two nucleus is called internuclear axis( bond axes键轴) x. ◼ sigma symmetrical orbital, such as s , px, dx2-y2, dz2; ◼ pi symmetrical orbital, such as py, pz, dxy, dyz, dxz