AP Chemistrymediummcq1 pt
Which is the electron configuration of Fe²⁺ (iron, Z = 26)?
A.[Ar] 3d⁶
B.[Ar] 4s² 3d⁴
C.[Ar] 3d⁴
D.[Ar] 4s² 3d⁸
Explanation
Core Concept
Neutral Fe is [Ar] 4s² 3d⁶. Transition-metal cations lose their 4s electrons first, so Fe²⁺ drops the 4s pair and keeps the six 3d electrons.
Correct Answer
A[Ar] 3d⁶
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