---
title: "Gaseous chromium atoms (\\(\\text{Cr}\\), \\(Z = 24\\)) exhibit an anomalous ground-state electron configuration compared to standard Aufbau predictions. Which of the following correctly identifies the ground-state electron configuration of a neutral \\(\\text{Cr}\\) atom and provides the correct physical justification?"
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url: "https://nerd-notes.com/ubq/123454/"
date_modified: "2026-09-28T11:59:48+00:00"
---

# Gaseous chromium atoms (\(\text{Cr}\), \(Z = 24\)) exhibit an anomalous ground-state electron configuration compared to standard Aufbau predictions. Which of the following correctly identifies the ground-state electron configuration of a neutral \(\text{Cr}\) atom and provides the correct physical justification?

Gaseous chromium atoms (\(\text{Cr}\), \(Z = 24\)) exhibit an anomalous ground-state electron configuration compared to standard Aufbau predictions. Which of the following correctly identifies the ground-state electron configuration of a neutral \(\text{Cr}\) atom and provides the correct physical justification?

- **A.** It is \([\text{Ar}]\,4s^1 3d^5\), because transferring an electron from the \(4s\) orbital to the \(3d\) subshell increases the effective nuclear charge experienced by the valence electrons.
- **B.** It is \([\text{Ar}]\,4s^1 3d^5\), because the energy difference between the \(4s\) and \(3d\) subshells is very small, and placing one electron in each of the \(6\) valence orbitals minimizes electron-electron repulsion compared to pairing two electrons in the \(4s\) orbital.
- **C.** It is \([\text{Ar}]\,4s^2 3d^4\), because completely filling the lower-energy \(4s\) subshell maximizes orbital overlap with core electrons and stabilizes the atom.
- **D.** It is \([\text{Ar}]\,4s^2 3d^4\), because electrons in the \(4s\) orbital are strictly lower in energy than those in the \(3d\) subshell for all neutral atoms, requiring the \(4s\) orbital to be fully occupied first.

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