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preface to fifteenth edition

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PROPERTIES OF ATOMS, RADICALS, AND BONDS 4.53<br />

TABLE 4.11<br />

Bond Dissociation Energies (Continued)<br />

Bond<br />

Hf 298 ,<br />

kJ/molBond<br />

Hf 298 ,<br />

kJ/mol<br />

Zirconium<br />

Zr9C 561(25)<br />

Zr9F 623(63)<br />

Zr9N 565(25)<br />

Zirconium (continued)<br />

Zr9O 760(8)<br />

Zr9S 575(17)<br />

Source: T. L. Cottrell, The Strengths of Chemical Bonds, 2d ed., Butterworth, London, 1958; B. deB. Darwent, National<br />

Standard Reference Data Series, NationalBureau of Standards, no. 31, Washing<strong>to</strong>n, 1970; S. W. Benson, J. Chem. Educ.<br />

42:502 (1965); and J. A. Kerr, Chem. Rev. 66:465 (1966).<br />

4.6 BOND AND GROUP DIPOLE MOMENTS<br />

Allbonds between equala<strong>to</strong>ms are given zero values. Because of their symmetry, methane and<br />

ethane molecules are nonpolar. The principle of bond moments thus requires that the CH 3 group<br />

moment equalone H9C moment. Hence the substitution of any aliphatic H by CH 3 does not alter<br />

the dipole moment, and all saturated hydrocarbons have zero moments as long as the tetrahedral<br />

angles are maintained.<br />

TABLE 4.12<br />

Bond Dipole Moments<br />

Bond Moment, D* Bond Moment, D*<br />

H9C<br />

Aliphatic 0.3<br />

Aromatic 0.0<br />

C9C 0.0<br />

C#C 0.0<br />

C9O<br />

Ether, aliphatic 0.74<br />

Alcohol, aliphatic 0.7<br />

C"O<br />

Aliphatic 2.4<br />

Aromatic 2.65<br />

O9H 1.51<br />

C9S 0.9<br />

C"S 2.0<br />

S9H 0.65<br />

S9O (0.2)<br />

S"O<br />

Aliphatic 2.8<br />

Aromatic 3.3<br />

C9N, aliphatic 0.45<br />

C"N 1.4<br />

C#N (nitrile) 3.6<br />

NC (isonitrile) 3.0<br />

N9H 1.31<br />

N9O 0.3<br />

N"O 2.0<br />

N (lone pair on sp 3 N) 1.0<br />

C9P, aliphatic 0.8<br />

P9O (0.3)<br />

P"O 2.7<br />

P9S 0.5<br />

P"S 2.9<br />

B9C, aliphatic 0.7<br />

B9O 0.25<br />

Se9C 0.7<br />

Si9C 1.2<br />

Si9H 1.0<br />

Si9N 1.55<br />

30<br />

* To convert debye units D in<strong>to</strong> coulomb-meters, multiply by 3.33564 10 .

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