Structure of Alkyl Halides Halogens increase in size going down the periodic table, so the C-X bond is longer as you go down periodic table C-X bond is weaker as you go down periodic table C-X bond is polarized with slight positive on carbon and slight negative on halogen TABLE 10.1 A Comparison of the Halomethanes Bond length Bond strength Dipole moment Halomethane (pm) (k]/mol) (kcal/mol) (0) CHaF 139 452 108 1.85 CHCI 178 351 84 1.87 CHgBr 193 293 70 1.81 CHI 214 234 56 1.62 Structure of Alkyl Halides „ Halogens increase in size going down the periodic table, so the C-X bond is longer as you go down periodic table „ C-X bond is weaker as you go down periodic table „ C-X bond is polarized with slight positive on carbon and slight negative on halogen