Which of the following are valid ionic Lewis structures? Drag each item to the appropriate bin. Which nonmetals could form an ionic compound with magnesium with the formula MgX2 (where X represents the nonmetal)? Drag each item to the appropriate bin.

For part 1)

[Na+][Br-] and [F-][Ca2+][F-] are valid, the rest are not. Both of these consist of metals (Na and Ca) bonded to very electronnegative nonmetals (F and Br). In such a case, the metal takes on a positive charge and the non-metal becomes negative, forming an ionic bond. Covalent, and ionic bonds with negatively charged metals are unrealistic and not accurate.

For part 2)

We want non metals that generally form X- (singly charged) ions. These are found in the next-to-last column of the periodic table (F down to At). In this column, we find F, Cl, and Br, and none of the others.

So, F, Cl, and Br are possible, N, S, and O are not.