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

1 Answer
anor277
Aug 20, 2017

From the #4s# subshell........#a.#

Explanation:

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

#1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)4s^(2)3d^n#

The ionic configuration of the #M^(2+)# cation is (usually)........

#[1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^n]^(2+)#

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

#Cr^(2+)# is a notable exception in that its #3d^(5)4s^1# possesses maximum multiplicity with respect to spin quantum number. Anyway, please consult your text.

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