Question

Ionic compounds are formed from ionic bonds, whereby an electron is transferred from the metal cation to the nonmetal anion. Ions form solid lattices of ions. Covalent compounds form solids through the attraction of two covalent molecules. Since the attraction between two covalent molecules is weak compared to the ionic bonds holding an ionic compound together, ionic compounds tend to have higher melting points.
Which of the following compounds has the highest boiling point?

I2
NaI
HI
IBr

Answer 1

Answer:

NaI

Explanation:

In I₂, HI and IBr, both atoms are nonmetals and they form covalent bonds in which electrons are shared.

In NaI, Na is a metal and I a nonmetal, so they form an ionic bond, where Na loses an electron to form Na⁺ and I gains an electron to form I⁻.  Anions and cations are attracted to each other through electrostatic forces.

Since ionic bonds are stronger than covalent bonds, more energy is required to break them in the melting process, thus having higher melting points.

All in all, NaI is the one with the highest melting point.