---
title: "A student uses photoelectron spectroscopy to compare equal numbers of gas-phase \\(\\text{Al}\\) atoms and \\(\\text{Al}^{+}\\) ions under identical conditions. In each spectrum, peak intensity is proportional to the number of electrons in the corresponding subshell. The \\(1s\\) peaks are omitted from the graph.  Which statement best explains why the \\(3s\\) peak undergoes a larger shift than the \\(n=2\\) peaks when \\(\\text{Al}\\) is oxidized to \\(\\text{Al}^{+}\\)?"
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url: "https://nerd-notes.com/ubq/120077/"
date_modified: "2026-08-21T08:41:15+00:00"
---

# A student uses photoelectron spectroscopy to compare equal numbers of gas-phase \(\text{Al}\) atoms and \(\text{Al}^{+}\) ions under identical conditions. In each spectrum, peak intensity is proportional to the number of electrons in the corresponding subshell. The \(1s\) peaks are omitted from the graph.

Which statement best explains why the \(3s\) peak undergoes a larger shift than the \(n=2\) peaks when \(\text{Al}\) is oxidized to \(\text{Al}^{+}\)?

A student uses photoelectron spectroscopy to compare equal numbers of gas-phase \(\text{Al}\) atoms and \(\text{Al}^{+}\) ions under identical conditions. In each spectrum, peak intensity is proportional to the number of electrons in the corresponding subshell. The \(1s\) peaks are omitted from the graph.

Which statement best explains why the \(3s\) peak undergoes a larger shift than the \(n=2\) peaks when \(\text{Al}\) is oxidized to \(\text{Al}^{+}\)?

![Draw a grayscale stick-spectrum graph with one plotting area. The horizontal axis is labeled “Binding energy, \(E_b\) \((\text{eV})\)” and spans \(0\) to \(130\); the vertical axis is labeled “Relative intensity” and spans \(0\) to \(6\). Include light gridlines at each stated peak coordinate. A legend maps a solid line to \(\text{Al}\) and a dashed line to \(\text{Al}^{+}\). The solid spectrum has vertical peaks at \(6\), \(10\), \(75\), and \(120\ \text{eV}\), with respective heights \(1\), \(2\), \(6\), and \(2\). The dashed spectrum has no peak at \(6\ \text{eV}\) and has vertical peaks at \(20\), \(78\), and \(123\ \text{eV}\), with respective heights \(2\), \(6\), and \(2\). Place subshell annotations \(3p\), \(3s\), \(2p\), and \(2s\) above the corresponding peak or paired peaks from left to right. No other curves, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1787301675-87KCrb.jpg)

- **A.** The remaining \(3s\) electrons become less tightly held because removing the \(3p\) electron decreases the shielding of the \(3s\) electrons.
- **B.** The remaining \(3s\) electrons become more tightly held because oxidation increases the number of protons in the nucleus and therefore increases \(Z_{\mathrm{eff}}\).
- **C.** The remaining \(3s\) electrons become more tightly held because removing the \(3p\) electron reduces valence-shell screening and electron-electron repulsion, whereas a \(3p\) electron provides little shielding for the \(n=2\) electrons.
- **D.** The \(n=2\) electrons undergo the larger oxidation-induced increase in attraction because their peaks have greater binding energies than the \(3s\) peak.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120077/*