---
title: "The ground-state electron configuration of a neutral iron atom, \\(\\text{Fe}\\), is \\([\\text{Ar}]\\,4s^2 3d^6\\). Which of the following identifies the correct ground-state electron configuration of the \\(\\text{Fe}^{2+}\\) ion and provides the correct justification for the order of electron removal?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/120161/"
date_modified: "2026-08-21T16:02:40+00:00"
---

# The ground-state electron configuration of a neutral iron atom, \(\text{Fe}\), is \([\text{Ar}]\,4s^2 3d^6\). Which of the following identifies the correct ground-state electron configuration of the \(\text{Fe}^{2+}\) ion and provides the correct justification for the order of electron removal?

The ground-state electron configuration of a neutral iron atom, \(\text{Fe}\), is \([\text{Ar}]\,4s^2 3d^6\). Which of the following identifies the correct ground-state electron configuration of the \(\text{Fe}^{2+}\) ion and provides the correct justification for the order of electron removal?

- **A.** \([\text{Ar}]\,4s^2 3d^4\), because electrons in the \(3d\) subshell are added last during the Aufbau filling sequence and are therefore the first to be removed during ionization.
- **B.** \([\text{Ar}]\,4s^2 3d^4\), because removing two electrons from the \(3d\) subshell minimizes electron-electron repulsions within the partially filled \(d\) orbitals.
- **C.** \([\text{Ar}]\,3d^6\), because electrons in the \(4s\) subshell experience a greater effective nuclear charge than electrons in the \(3d\) subshell, making them less tightly held by the nucleus.
- **D.** \([\text{Ar}]\,3d^6\), because electrons in the \(4s\) subshell have a higher principal quantum number (\(n = 4\)) and are on average located farther from the nucleus, making them the valence electrons removed first.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120161/*