s character in bond－nzphddr的部落格

標題:

s character in bond

發問:

CH bond in benzene has a higher s character, thus has more effective overlap. The bond pairs of e- in CH bond in benzene is held closer to the nuclei. Why higher s character, more effective overlap and e- held closer ot nuclei?

最佳解答:

This can be explained in form of hybridization. Study the following data carefully. For sp hybridization, s character is 50% while p character is also 50% For sp2 hybridization, s character is 33% while p character is also 67% For sp3 hybridization, s character is 25% while p character is also 75% For both sp and sp2 hybridization, they have more s character comparing p character. This implies, more electrons from s will be close(接近) to nucleus. This is due to the penetrating effect, which indicates s orbital having a greater chance to move towards the nucleus than that of p- and d- orbital! In the light of a general principle, the closer the distance between the electron density (provided by s) and nucleus /nuclei, the stronger is the electron - nuclei/nucleus attraction. And the stronger is the bond energy. As benzene, each carbon is sp2 hybridized. This signifies each of them has a higher s character than p. Hence the electron - nuclei/nucleus attraction is strong. This also means their overlaps are also effective. Give you a question to think about: For sp3 hybridization, such as methyl group, is considered as electron donatinggroup. Why? Check mail for the answer to this question.