Which of the following elements forms an ion that is smaller in radius than a Ca^{2+} ion?

In the ionic compounds LiF, NaCl, KBr, and RbI, the measured cation–anion distances are 2.01 Å (Li–F), 2.82 Å (Na–Cl), 3.30 Å (K–Br), and 3.67 Å (Rb–I), respectively. c. What estimates of the cation–anion distance would you obtain for these four compounds using neutral atom bonding atomic radii? Are these estimates as accurate as the estimates using ionic radii?

For each set of atoms and ions, pick the smallest one.

a. I, I+, I−

b. Be2+, Ca2+, Mg2+

c. Fe, Fe2+, Fe3+

Identify each statement as true or false: (c) Cl^- is bigger than I^-.