Question
Three metals and their ions are shown below Which metal would form compounds with the lowest melting point? magnesium Lithium Li^+ Magnesium Mg^2+ Aluminium Al^3+
Answer
4.6
(257 Votes)
Delilah
Veteran · Tutor for 9 years
Answer
Lithium
Explanation
Melting points are determined by the type and strength of bonds in a compound. Typically, 1. Ionic compounds which form crystal lattices have high melting points because the strong electrostatic forces between positive and negative ions require much heat to break. The more charged the ion, the stronger this attraction.2. Generally, metals in Group 1 (like lithium Li+) form +1 ions, Group 2 metals (like magnesium Mg2+) form +2 ions, and aluminum being in Group 13 forms +3 ions.Here we see thata. Lithium forms Li+ with +1 charge.b. Magnesium forms
with +2 charge.c. Aluminum forms
ions with +3 charge. The strength of ionic bonds, and consequently the melting points, increase with greater charge. It means the metal ions with greater charge will attract more heavily to the other ion and form a compound with high melting point. Therefore, Li+ will form bonds that are weaker than the bonds
and
would form, given that Li+ has less positive charge.This would mean the compounds formed by Lithium will have the lowest melting point out of the given options.