A PES spectrum of an unknown gaseous element shows the following peaks (leftward…
CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
A PES spectrum of an unknown gaseous element shows the following peaks (leftward direction corresponds to increasing binding energy). Relative heights are proportional to the number of electrons in each peak.
Peak
Binding energy / kJ mol⁻¹
Relative height
1
3
1
2
10
6
3
15
2
4
70
6
5
90
2
6
1180
2
Respond to the prompts below.
(a) Identify the element that produced this spectrum. Clearly explain how both the peak heights and binding energies lead to your conclusion.
(b) Write the complete ground-state electron configuration of the element.
(c) Although peaks 2 and 3 both arise from n = 3 electrons, peak 3 appears at the higher binding energy. Explain this observation in terms of subshell shielding and penetration.
(d) Predict qualitatively how the spectrum would change (in both peak presence and binding energies) if the element were converted to its common +2 oxidation state in the gas phase. Provide reasoning for each predicted change.