Why are the $\mathrm{O}-\mathrm{F}$ bonds in ${\mathrm{O}}_2{\mathrm{F}}_2$ longer than that in ${\mathrm{OF}}_2$ whereas the $\mathrm{O}-\mathrm{O}$ bond in ${\mathrm{O}}_2{\mathrm{F}}_2$ is shorter than that in ${\mathrm{H}}_2{\mathrm{O}}_2$?

Draw the shapes of the following molecules and ions, showing the positions of the lone pairs of electrons:

$\mathrm{ClF}, {\mathrm{BrF}}_3, {\mathrm{IF}}_5, {\mathrm{IF}}_7, {\mathrm{I}}_3^{-}, {\mathrm{ICl}}_4^{-}$ and ${\mathrm{I}}_5^{-}$