Which shows the order of decreasing atomic size? a. Si, Al, Mg, Na
b. I, Br, CI, F
c. Be, Mg, Ca, Sr
d. C, P, Se, I

There is one s orbital, and there are three p orbitals, five d orbitals, and seven f orbitals. thus, the answer is b. do not confuse the number of orbitals in a subshell with the number of electrons the subshell can hold. each orbital can hold two electrons, so the capacity of an nf subshell is 14 electrons.