Question

Place the following in order of increasing radius.

Ca2+ S2- Cl-
A.S2- < Cl- < Ca2+
B.Cl- < Ca2+ < S2-
C.Ca2+ < S2- < Cl-
D.Cl- < S2- < Ca2+
E.Ca2+ < Cl- < S2-

Answer 1

To order Ca2+, S2-, and Cl- by increasing radius, refer to ionic size trends and consider the nuclear charge. The correct order is Ca2+ < Cl- < S2-.

Step-by-step explanation:

The question asks to place the ions Ca2+, S2-, and Cl- in order of increasing radius. According to the periodic table and atomic radii trends, ionic size decreases with an increased nuclear charge (or more protons) for ions with the same number of electrons. Since S2-, Cl-, and Ca2+ are isoelectronic (all having the same number of electrons as the noble gas Argon), the radius of these ions will increase as we move from a higher nuclear charge to a lower nuclear charge. So, Ca2+ has the smallest radius as it has the greatest nuclear charge, and S2- has the largest radius because it has the least nuclear charge.

To put them in order of increasing radius: Ca2+ < Cl- < S2-. Thus the correct answer is E. Ca2+ < Cl- < S2-.