Using valence bond approach, predict the shape and magnetic character of :
(i) `[Ni(CO)_(4)]` (ii) `[NiCl_(4)]^(2-)` [Atomic number of Ni = 28]

Explanation

(i) `[Ni(CO)_(4)]`.
`Ni(28) : 4s^(2)3d^(8), Ni(0) : 4s^(0) 3d^(10)` , CO is a strong field ligand, therefore, two 4s electrons are paired with 3d electrons. `sp^(3)` hybridisation takes place

It has tetrahedral shape and is diamagnetic in nature.
(ii) `[NiCl_(4)]^(2-),Ni^(2+):4s^(0)3d^(8)`

It is tetrahedral in shape and paramagnetic in nature due to the presence of two unpaired electrons.