Which of the following represents the ground-state electron configuration of Fe^{3+}?

• A. [Ar] 4s^2 3d^3
• B. [Ar] 3d^5
• C. [Ar] 3d^6
• D. [Ar] 3d^3

Answer: (B)

Verified step by step guidance

1. Step 1: Identify the atomic number of iron (Fe), which is 26. This means a neutral Fe atom has 26 electrons.
2. Step 2: Write the ground-state electron configuration for neutral Fe. The configuration is \([Ar] 4s^2 3d^6\), where \([Ar]\) represents the electron configuration of argon (18 electrons).
3. Step 3: Understand that Fe\(^{3+}\) means the iron ion has lost 3 electrons. Electrons are removed first from the outermost shell, which is the 4s orbital, followed by the 3d orbitals.
4. Step 4: Remove 2 electrons from the 4s orbital and 1 electron from the 3d orbital to account for the 3+ charge. This results in the configuration \([Ar] 3d^5\).
5. Step 5: Confirm that \([Ar] 3d^5\) is the correct ground-state electron configuration for Fe\(^{3+}\), as it reflects the loss of three electrons from the neutral atom.