CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
Two unknown elements, X and Y, taken from Period 4 of the periodic table, have the following PES data collected with the same photon energy. Peak intensities are proportional to electron count; the x-axis increases to the right.
Spectrum X:
• Peak α at 400eV (height 2)
• Peak β at 92eV (height 6)
• Peak γ at 22eV (height 2)
Spectrum Y:
• Peak m at 400eV (height 2)
• Peak n at 92eV (height 6)
• Peak o at 46eV (height 5)
• Peak p at 18eV (height 1)
Assume peaks appear in order of decreasing binding energy from left to right.
(a) For each spectrum, list the subshell assignment and electron count associated with every peak.
(b) Identify which spectrum corresponds to calcium and which corresponds to scandium. Support your answer by citing two specific spectral features that distinguish the two elements.
(c) Using electron-configuration arguments, explain why one of the spectra exhibits an additional peak between 46eV and 18eV that is absent in the other spectrum.
(d) Predict how the position of the 3d-related peak would change if scandium were ionized to Sc3+ before analysis, and justify your prediction in terms of effective nuclear charge experienced by the remaining electrons.