chemistry- polarity

i was doing a past paper question...
'in which of the following compounds is the anion most polarized:
-LiF
-LiI
-KF
-KI
the answer is LiI.
i dont understand why this is, because LiF has the largest electronegativity difference!??????????

Reply 1

gd99

I think it has something to do with LiF being ionically bonded, so cannot be polar. However, I think LiI is ionically bonded, but with covalent character, so can be polar. Not sure that’s totally correct, but it would be my best guess!