Which of the following correctly lists the five atoms in order of increasing size (smallest to largest)? Why?

Question

a. F < K < Ge < Br < Rb

b. F < Ge < Br < K < Rb

c. F < K < Br < Ge < Rb

d. F < Br < Ge < K < Rb

Answer 1

d. F < Br < Ge < K < Rb

This is because atomic size increases going from right to left across the period table, and going down within a group.  This is related to the number of orbitals and the number of protons in the nucleus.