A laboratory technician collected a high-resolution photoelectron spectrum (PES) of a…
CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
A laboratory technician collected a high-resolution photoelectron spectrum (PES) of a pure element in the gas phase. The spectrum shows four distinct peaks, listed here from greatest to least binding energy (all energies in kJ·mol⁻¹, peak areas in arbitrary units proportional to electron count):
• Peak W: 1 320 kJ·mol⁻¹, area ≈ 2
• Peak X: 400 kJ·mol⁻¹, area ≈ 2
• Peak Y: 115 kJ·mol⁻¹, area ≈ 6
• Peak Z: 20 kJ·mol⁻¹, area ≈ 5
Assume the sample consists of atoms in their ground electronic state.
(a) Associate each peak (W, X, Y, Z) with a specific electron subshell in the atom, and justify your assignments using both binding-energy magnitude and relative peak area.
(b) Using the peak areas, determine the total number of electrons in a single atom of the element. Explain each step in your reasoning.
(c) Confirm that the total electron count is consistent with the position of the element on the periodic table, and write the ground-state electron configuration using spectroscopic notation.
(d) The measured area of Peak Z is slightly lower than the ideal integer value predicted by theory. Provide one experimental factor that could cause such a deviation and explain its effect on the recorded spectrum.