The bond length $\left(\mathrm{pm}\right)$ of ${\mathrm{F}}_2,{\mathrm{H}}_2,{\mathrm{Cl}}_2$and ${\mathrm{I}}_2$ respectively is

• As we move up to down in periodic table bond length increases. Higher is the atomic size, higher is the bond length and vice versa.
• Iodine has the highest atomic size. Hence, the bond between I - I would be high.
  The bond length $\left(\mathrm{pm}\right)$ of ${\mathrm{F}}_2,{\mathrm{H}}_2,{\mathrm{Cl}}_2$ and ${\mathrm{I}}_2$, respectively is $144,74,199,267 .$

$\mathrm{Bond} \mathrm{length} \mathrm{\alpha } \mathrm{atomic} \mathrm{size}$