化學(xué)競賽雜化軌道理論-文庫吧資料
2025-01-19 11:02本頁面
【正文】 . Valence bond theory treatment of ?bonding: the bonding in the nitrate anion O NOOThere are three “objects” around N so the geometry is trigonal planar. The shape is given by AX3 (trigonal planar). 2s 2p N N+ O 2s 2p O 2s 2p O 2s 2p sp2 2p N+*(sp2) ? ? ? ? The overlap of the sp2 hybrid orbitals on N with the the 2p orbitals on the O give the three (sp22p) ? bonds and it is the overlap of the “l(fā)eft over” p orbital on N with the appropriate orbital on the uncharged O atom that forms the (2p2p) ? bond. N OOON N 64?價鍵理論 －－共振結(jié)構(gòu) VBT gives only one of the canonical structures at a time. NOOONOOO NOOO分子軌道理論－－離域 ?鍵 MO gives delocalized ?orbital C6H6 (benzene) ?bonds Each C uses sp2 orbitals to form 3 ?bonds 1 p orbital on each C remains 價鍵理論－－共振結(jié)構(gòu) HHHHHH HHHHHHC6H6 (benzene) delocalized ?bonds 分子軌道理論－－離域 ?鍵 66?? frame work ? resonance Delocalized ? bond 離域 ?鍵 Conditions that favor the formation of delocalized ? bond i. The atoms are coplanar, with every atom contributing a porbital orientated in the same direction. 原子共平面，每個原子提供一個同取向的 p軌道 ii. The number of ? electrons is less than twice the number of the participating porbitals. ?電子數(shù)小于軌道數(shù) 2被 mn ?norbital numbers, melectron numbers (n2) NO OO s p2N s p2C s p2?1 09NH HN s p2C s p2?87H HN s p2C s p2?66Nu n f a v o r a b l eDelocalized ? bond Phenolphthalein is an anic pound (C20H14O4) used as an acidbase indicator. The pound is colorless in acidic solution and pinkish in basic solution (with the transition occuring around pH 9). 酚酞變色原因 H OCO HCOOH OCOCOO N aN a O HH 2 Os p3s p2sp 2p C*(sp) O 2s 2p O 2s 2p 2s 2p C ? ? ? ? O C O 43?C OO167。 from each other and 90176。 In the case dsp3, the axial bond length is shorter, While it is longer in the case sp3d （ dsp3 雜化 軸向鍵長較短， sp3d雜化則較長 PF5 3s 3p P P* 3d P* (sp3d) 3d We need hybrid orbitals suitable for bonds to 5 atoms. ns and np binations can only provide four, so we need to use nd orbitals (if they are available). 3dz2 3pz 3py 3px 3s sp3dz2 The appropriate mixture to form a trigonal bipyramidal arrangement of hybrids involves
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