2.Formation and characteristics of covalent bond The principles of forming a covalent bond: .The unpaired valence electrons have opposite spin directions; .Maximum overlap of the atomic orbits. The characteristics of the covalent bond: Character of saturation(饱和性) 22 Character of direction(方向性) e.g.:H-CI (H:1S1;Cl:3s23p5) His and Cl3px overlap along x axis2.Formation and characteristics of covalent bond The principles of forming a covalent bond: •The unpaired valence electrons have opposite spin directions； •Maximum overlap of the atomic orbits. The characteristics of the covalent bond ： •Character of direction(方向性 ) •Character of saturation(饱和性 ) e.g.: H-Cl (H: 1S 1; Cl: 3s 23p 5 ) H1s and Cl3px overlap along x axis z2