Tabulated Data
| Bond | Bond | Bond-dissociation energy | Comment | |
|---|---|---|---|---|
| (kcal/mole) | (kJ/mole) | |||
| C-H | C-H bond | 98 | 410 | C-H bond strength affected by substituents (see next table) |
| C-F | C-F bond | 117 | 490 | one of the strongest single bonds to carbon |
| C-Cl | C-Cl bond | 79 | 331 | more labile than C-H and C-F bonds, chlorocarbons degrade photochemically |
| C-Br | C-Br bond | 69 | 285 | weaker than C-Cl bonds bromocarbons are often labile and are useful fire retardants |
| C-C | C-C bond | 83-85 | 347-356 | strong, but weaker than C-H bonds |
| Cl-Cl | chlorine | 58 | 242 | indicated by the yellowish colour of this gas |
| Br-Br | bromine | 46 | 192 | indicated by the brownish colour of Br2 source of the Br. radical |
| I-I | iodine | 36 | 151 | indicated by the purplish colour of I2 source of the I. radical |
| H-H | hydrogen | 104 | 436 | strong, nonpolarizable bond cleaved only by metals and by strong oxidants |
| O-H | hydroxyl | 110 | 460 | comparable to strength of O=O and C-H bonds |
| O=O | oxygen | 119 | 497 | strong bond, but O-H bonds are of comparable strength |
| N≡N | nitrogen | 226 | 945 | one of the strongest bonds production of ammonia consumes significant energy |
The data tabulated above shows how bond strengths vary over the periodic table. There is great interest, especially in organic chemistry, concerning bond strengths of bonds within a given group of compounds.
| Bond | Bond | Bond-dissociation energy | Comment | |
|---|---|---|---|---|
| (kcal/mole) | (kJ/mole) | |||
| H3C-H | Methyl C-H bond | 105 | 439 | One of the strongest aliphatic C-H bonds |
| C2H5-H | Ethyl C-H bond | 101 | 423 | slightly weaker than H3C-H |
| (CH3)3C-H | tertiary C-H bond | 96.5 | 404 | tertiary radicals are stabilized |
| CH2CH-H | vinyl C-H bond | 111 | 464 | vinyl radicals are rare |
| HC2-H | acetylenic C-H bond | 133 | 556 | acetylenic radicals are very rare |
| C6H5-H | phenyl C-H bond | 113 | 473 | comparable to vinyl radical, rare |
| CH2CHCH2-H | allylic C-H bond | 89 | 372 | such bonds show enhanced reactivity |
| C6H5CH2-H | benzylic C-H bond | 90 | 377 | akin to allylic C-H bonds such bonds show enhanced reactivity |
| H3C-CH3 | Alkane C-C bond | 83-85 | 347-356 | much weaker than a C-H bond |
| H2C=CH2 | Alkene C=C bond | 146-151 | 611-632 | about 2x stronger than a C-C single bond |
| HC≡CH | alkyne C≡C triple bond | 200 | 837 | about 2.5x stronger than a C-C single bond |
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