Question

Which of the following is the correct electron configuration for the ion \(\text{Fe}^{3+}\)?

• A. [Ar] 3d\(^6\)
• B. [Ar] 3d\(^5\)
• C. [Ar] 4s\(^2\) 3d\(^3\)
• D. [Ar] 3d\(^8\)

Hint:

When an atom forms a positive ion, electrons are removed starting from the outermost orbitals, typically 4s before 3d.

Answer 1

The Correct Option is A

Iron (Fe) has an atomic number of 26, so its electron configuration in the neutral state is: \[ \text{Fe}: [Ar] 4s^2 3d^6 \] When iron loses 3 electrons to form the \(\text{Fe}^{3+}\) ion, the electrons are removed first from the 4s orbital and then from the 3d orbitals: \[ \text{Fe}^{3+}: [Ar] 3d^6 \] Thus, the electron configuration for \(\text{Fe}^{3+}\) is [Ar] 3d\(^6\). Answer: The correct electron configuration is [Ar] 3d\(^6\), so the correct answer is option (1).