S. No.

Outer configu-ration

No. of unpaired $e^-$

Colour of ion

Magnetic moment

${V^{ + 3}}$

$3{d^2}$

$2$

Green

$2.76$

$M{n^{ + 3}}$

$3{d^4}$

$4$

Violet

$1.9$

$F{e^{ + 3}}$

$3{d^5}$

$5$

Yellow

$5.96$

$C{u^{ + 2}}$

$3{d^9}$

$1$

Blue

$1.9$