Question

Only iodine forms heptafluoride $I{F}_7$, but chlorine and bromine give pentafluorides. The reason for this is :

• A. low electron affinity of iodine
• B. unusual pentagonal bipyramidal
• C. that the larger iodine atom can accommodate more number of smaller fluorine atom around it
• D. low chemical reactivity of $I{F}_7$

Answer 1

Answer: (C)

that the larger iodine atom can accommodate more number of smaller fluorine atom around it

The ionic radius of iodine is grater than the ionic radius fo chlorine or bromine.
Hence, iodide ion can accommodate more $F$ atoms than chloride or bromide ion can.
Hence, iodine forms hepta fluoride whereas chlorine or bromine forms penta fluoride only.