Lesson 6: 1.6 Photoelectron Spectroscopy (PES)
Duration of Days: 1
Lesson Objective
Explain the relationship between the photoelectron spectrum of an atom or ion and its ground-state electron configuration and nuclear-electron interactions.
How does PES provide direct, experimental evidence for the shell and subshell models of the atom?
What do the position (x-axis) and the height (y-axis) of a PES peak represent?
Photoelectron Spectroscopy (PES)
Binding Energy
Ionization Energy
Peak Intensity/Height
Learning Objective 1.6.A; Suggested Skill 4.B (Model Analysis)
PES provides the experimental proof for the electron configurations taught in Topic 1.5. Students must understand that the binding energy (x-axis, often plotted backwards) relates to Coulombic attraction to the nucleus, while peak height (y-axis) relates to the relative number of electrons in that subshell.
Support: Have students practice a matching activity where they align standard electron configurations directly underneath their corresponding PES graphs.
Extension: Present two PES graphs of adjacent elements on the periodic table (e.g., Boron and Carbon). Have students analyze why Carbon's 1s peak is shifted further to the left (higher binding energy) than Boron's.
Provide an unlabeled PES spectrum and require students to identify the element, write its electron configuration, and justify their response based on peak positions and heights.