higher melting point

[606419499]

If we have CHI3 vs CHF3 why would the Iodide cause the molecule to have a higher normal melting point? I based it off CHF3 being more electronegative but Iodide is also a bigger atom.

[Chem_Mod]

Hello,
When considering melting point, we must consider the IMFs that occur within solutions of these molecules.
F is more electronegative than I, meaning that CHF3 experiences stronger dipole dipole interactions than CHI3.
However, since I is a much larger molecule than F, CHI3 will have far stronger London Dispersion Forces, meaning its melting point will be higher.
In this case, because I is so much larger than F and far more polarizable, London Dispersion Forces play a greater role than dipole dipole forces.