A comparison of the valence regions of the photoelectron spectra of Na (Period 3) and…
CHEMISTRY · Single correct · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
A comparison of the valence regions of the photoelectron spectra of Na (Period 3) and K (Period 4) shows that the valence peak for K occurs at a lower binding energy than that for Na. Which statement best accounts for this observation?
(a) K has a greater nuclear charge, so its valence electron is pulled more strongly, requiring less energy to remove it.
(b) The 4s valence electron in K is in a higher principal energy level, so the greater distance and increased shielding more than offset the larger nuclear charge, giving it a lower binding energy.
(c) Because the inner electrons in K do not shield effectively, its valence electron feels almost the full nuclear charge, producing the lower binding energy observed.
(d) The valence electron of K occupies a 3d subshell that lies closer to the nucleus than Na’s 3s electron, explaining the lower binding energy.