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How many unpaired electrons are present in 26Fe3+?...

How many unpaired electrons are present in 26Fe3+?

A.

4

B.

2

C.

3

D.

5

Correct answer is D

There are 5 unpaired electrons present in 26Fe3+.

The atomic number of iron is 26, so it has 26 electrons. When iron loses 3 electrons to form Fe3+, it loses 2 from the s orbital and 1 from the d orbital. This leaves 5 unpaired electrons in the d orbital.

The electron configuration of Fe3+ is [Ar]3d5. The 5 d electrons are all unpaired because Hund's rule states that electrons will occupy degenerate orbitals singly before they pair up. This is because unpaired electrons have a lower energy than paired electrons.