SolutionsIonic Structures
1. Positive and negative ions
State the ions that make up K2O, Na2S, NaI and CaBr2.
- K2O: K+ and O2−
- Na2S: Na+ and S2−
- NaI: Na+ and I−
- CaBr2: Ca2+ and Br−
Metals form the positive ions and nonmetals the negative ones.
2. LiF or LiI
Which melts at a higher temperature, LiF or LiI? Why?
LiF. The Li+ and F− ions are more similar in size (r+/r− closer to 1): they pack better, the lattice energy is higher and a higher temperature is needed to melt it.