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Bond order, bond length, and bond energy are interrelated: higher bond order = shorter bond length = higher bond energy (stronger bond). For carbon-carbon bonds: C-C (154 pm, 347 kJ/mol, order 1), C=C (134 pm, 614 kJ/mol, order 2), C triple C (120 pm, 839 kJ/mol, order 3). Note that energy does NOT scale linearly with order because pi bonds are weaker than sigma bonds. For the oxygen series: O2+ (112 pm, BO 2.5), O2 (121 pm, BO 2), O2- (126 pm, BO 1.5), O2^2- (149 pm, BO 1). Resonance affects bond order: in CO3^2-, all C-O bonds have order 4/3 = 1.33, intermediate between single and double bonds. Bond energy exception: F-F (159 kJ/mol) is weaker than Cl-Cl (242 kJ/mol) due to lone pair-lone pair repulsion in the tiny F2 molecule. This is a common JEE trap. Bond polarity increases with electronegativity difference between atoms.