Bond length and bond strength correlation Is bond strength inversely proportional to bond length? As the bond length decreases, does the bond strength increase?
Decrease in bond length and increase in strength is only a trend, that is observed only between the same pairs of atoms, so its approximately true for C C bonds, single, double triple and similarly for N N bonds. But in general this is not true as can be seen in the following list of bonds with  approximately the same length e.g. 
$\ce{H-Br,141 pm 366} \pu{ kJ mol^{-1}}$ 
$\ce{F-F, ~142 , ~~~~158}$
$\ce{C-O, 143 ,  ~~~~360}$
$\ce{O-O, 148 ,  ~~~145}$
$\ce{N-N, 145 ,  ~~~170}$