# What is the electronic configuration of the first row transition metals and their dications? Why is the configuration of Cr^(2+) unusual?

Aug 20, 2017

From the $4 s$ subshell........$a .$

#### Explanation:

The atomic configuration of the first row transition series is....:

$1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{2} 3 {d}^{n}$

The ionic configuration of the ${M}^{2 +}$ cation is (usually)........

${\left[1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 3 {d}^{n}\right]}^{2 +}$

The $4 s$ electrons are conceived to be removed FIRST upon ionization. And for the explanation, you will have to consult your text. Note that the $3 d$ and $4 s$ electrons are very close in energy, and their relative energies may change upon ionization.

$C {r}^{2 +}$ is a notable exception in that its $3 {d}^{5} 4 {s}^{1}$ possesses maximum multiplicity with respect to spin quantum number. Anyway, please consult your text.