The bond enthalpies for these bonds are: C-C 347 kJ/mol C-N 276 kJ/mol C-O 351 kJ/mol Why is carbon-nitrogen bond enthalpy lower? What factor makes that? And also the halogens bond enthalpies: F-F 157 kJ/mol Cl-Cl 243 kJ/mol Br-Br 193 kJ/mol I-I 151 kJ/mol Why has fluorine lower enthalpy? I suppose a polarizability plays a role - iodine is highly polarizable, so when approaching two atoms of iodine, they make large dipoles so they do great work... or something like that. Is it true?