Number of unpaired electrons present in the ground state of Fe3+ are (Atomic number of Fe = 26).
Correct answer: C. Five
- A. Three
- B. Four
- C. Five
- D. Six
Explanation
Neutral iron is [Ar] 3d6 4s2, and forming Fe3+ removes both 4s electrons and one 3d electron, leaving 3d5. By Hund's rule those five electrons occupy the five d orbitals singly with parallel spins, so all five are unpaired, and that half filled arrangement is what makes Fe3+ so stable. Removing d electrons before the 4s pair is the standard error.
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About Electronic Configuration
Electronic configuration describes how electrons occupy shells, subshells and orbitals around an atom. Questions use the Aufbau principle, Pauli exclusion principle and Hund's rule to write configurations, identify valence electrons, form ions and explain periodic trends, including common exceptions such as chromium and copper.
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