NONEQUIVALENT HYBRID ATOMIC ORBITALS 23 s+Py add S-Py 2 Figure 1.47.The etwo hybrid sp atomic shaded and unshaded area represent obes of different mathematical signs. 1.48 HYBRIDIZATION INDEX This is the superscripton the p in an sp*hybrid orbital:such an orbital possesses [x/(1+x)](100)percent p character and [1/(1+x)](100)percent s character. The hybridiation index of an sporbita is(p-character)for an orbital,it is 0.894(47.2%p-character). 1.49 EQUIVALENT HYBRID ATOMIC ORBITALS A set of hybridized orbitals,each member of which possesses precisely the same value for its hybridization index. Example.If the atomic orbitals 2s and 2p,are distributed equally in two hybrid orbitals,each resulting orbital will have an equal amount of s and p character;that is,each orbital will be sp (sp00)(Fig.1.47).If the 2s and two of the 2p orbitals are distributed equally a nong three hybrid orbitals.each of the three e quivalent orbitals will bes(Fig. 1.49).Combinin ith thr gives four equivalent hybri of the oitals has an saual amout of s character.I+1025%.and an equal amount of p character,[3/(1 +3)]X 100%=75%. 1.50 NONEQUIVALENT HYBRID ATOMIC ORBITALS The hybridized orbitals that result when the constituent atomic orbitals are not1.48 HYBRIDIZATION INDEX This is the superscript x on the p in an spx hybrid orbital; such an orbital possesses [x/(l  x)] (100) percent p character and [1/(1  x)] (100) percent s character. Example. The hybridization index of an sp3 orbital is 3 (75% p-character); for an sp0.894 orbital, it is 0.894 (47.2% p-character). 1.49 EQUIVALENT HYBRID ATOMIC ORBITALS A set of hybridized orbitals, each member of which possesses precisely the same value for its hybridization index. Example. If the atomic orbitals 2s and 2pz are distributed equally in two hybrid orbitals, each resulting orbital will have an equal amount of s and p character; that is, each orbital will be sp (s1.00p1.00) (Fig. 1.47). If the 2s and two of the 2p orbitals are distributed equally among three hybrid orbitals, each of the three equivalent orbitals will be sp2 (s1.00p2.00) (Fig. 1.49). Combining a 2s orbital equally with three 2p orbitals gives four equivalent hybrid orbitals, s1.00p3.00 (sp3 ); that is, each of the four sp3 orbitals has an equal amount of s character, [1/(1  3)] 100%
25%, and an equal amount of p character, [3/(1  3)] 100%
75%. 1.50 NONEQUIVALENT HYBRID ATOMIC ORBITALS The hybridized orbitals that result when the constituent atomic orbitals are not equally distributed among a set of hybrid orbitals. NONEQUIVALENT HYBRID ATOMIC ORBITALS 23 add subtract s s + py s − py py φ1 φ2 Figure 1.47. The two hybrid sp atomic orbitals, φ1 and φ2. The shaded and unshaded areas represent lobes of different mathematical signs. c01.qxd 5/17/2005 5:12 PM Page 23