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