Question

How many unpaired electrons are present in Fe⁺² , Cr⁺³ , Cu⁺¹.

Answer 1

Fe(II) ion has Electronic configuration as: [Ar] 3d⁶ 4s² , the 'd' orbital can accommodate 10 electrons i.e. 5 pairs thus presence of 6 electrons means only one pair of electrons and 4 unpaired electron.

Similarly, Cr(III) Ion has : [Ar] 3d³ i.e. 3 Unpaired electrons

Cu(I) ions has : [Ar] 3d¹⁰ i.e. no unpaired electrons