1. The problem statement, all variables and given/known data 45. Consider the ions Li+, Na+, Be2+, and Mg2+. Which two are closest to one another in size? (A) Li+ and Na+ (B) Be2+ and Mg2+ (C) Be2+ and Li+ (D) Li+ and Mg2+ 2. Relevant equations N/A 3. The attempt at a solution I thought it wouldn't be A, B, or D due to the pairs having different outer electron shells. I thought C would be the correct answer since they are isoelectronic and thought that the extra proton would not make too large of a difference in radius.