Question

Write down the number of 3d electrons in the following ion:

Ni²⁺

Indicate how would you expect the five 3d orbitals to be occupied for this hydrated ions (octahedral).

Answer 1

Metal ion	Number of d-electrons	Filling of d-orbitals
Ni2+	8	\[\ce{t^6_{2g}e^2_g}\]

Answer 2

Ni²⁺: 3d⁸

Filling of orbitals in octahedral hydrated ion:

Ni²⁺: \[\ce{t^6_{2g}e^2_g}\]

↑	↑	eg
↑↓	↑↓	↑↓	t2g

(2 unpaired electrons)