Question

question 13 of 25 which of the following has the smallest radius? a. rb b. rb+ c. k+ d. k

Explanation:

Step1: Understand ionic and atomic radius trends

Atomic radius decreases across a period and increases down a group in the periodic table. Cations have smaller radii than their parent atoms as they lose electrons, reducing electron - electron repulsion and increasing the effective nuclear charge on the remaining electrons.

Step2: Analyze Rb and Rb+

Rb is in Group 1 and Period 5. Rb+ is formed by losing one electron. Rb+ has a smaller radius than Rb because of the loss of an electron shell and increased effective nuclear charge.

Step3: Analyze K and K+

K is in Group 1 and Period 4. K+ is formed by losing one electron. K+ has a smaller radius than K for the same reason as Rb and Rb+ (loss of an electron and increased effective nuclear charge).

Step4: Compare Rb+ and K+

Since K+ is in a higher period (Period 4) compared to Rb+ (Period 5), K+ has fewer electron shells. As the number of electron shells decreases, the atomic/ionic radius decreases. So, K+ has a smaller radius than Rb+.

Answer:

C. K+