s-psisp-p11
11 s − s s − p p - p
S-SPx-sP--P-Px-Px(b) 元 bond(a) bondsFigure9-3Schematic of bondsandπbonds12
12 + x + s-s + x - + px-s + x - + px-px - (a) σ bonds + + - - x z z pz-pz (b) π bond Figure 9-3 Schematic of σ bonds and bonds
Table 9-1 Comparisons of bond and π bondPi BondsBondingSigma BondsAlong the directionWays to overlapAlong the bondperpendicularto theaxesbondaxessmallOverlap extentlargesmallBond energylargeRelativelydifficultytoReactivityEasy to reacttakepartinreactions13
13 Table 9-1 Comparisons of σ bond and bond Bonding Sigma Bonds Pi Bonds Ways to overlap Along the bond axes Along the direction perpendicular to the bond axes Overlap extent large small Bond energy large small Reactivity Relatively difficulty to take part in reactions Easy to react
元20NN元yFigure 9-4 Schematic of bonds in nitrogen moleculeSingle bond: g bondDouble bond: g bond + 元 bondTriple bond: o bond + 2元 bond14
14 N N πy πz σ Figure 9-4 Schematic of bonds in nitrogen molecule. Single bond: σ bond Double bond: σ bond + bond Triple bond: σ bond + 2 bond
1XFigure9-5Schematic ofHzS molecule forming共价键的本质：核对负电区域的吸引。15
15 + + x y + + - - Figure 9-5 Schematic of H2S molecule forming. 共价键的本质：核对负电区域的吸引