Q81P - Chemistry: Molecular Nature Of Matter And Change

Question

According to valence bond theory, what set of orbitals is used by a Period 4 metal ion in forming 

(a) a square planar complex 

(b) a tetrahedral complex

Step-by-Step Solution

Answer

Following are the sets of orbitals used to a period 4 metal ion to form a square planar complex and a tetrahedral complex

 

a) One 3d, one 4s and two 4p orbitals mix

b) Two 3d, one 4s and three 4p orbitals mix

Step 1: Following metal ion orientation has to be formed

(a) a square planar complex 

(b) a tetrahedral complex

Step 2: Valence bond theory will be used here

Valence bond theory explains us that the ligand's orbital that is filled overlaps with the empty orbital of the metal ion; ligands donate their electron pairs, metal ion accepts them and the coordination covalent bond is formed.

Step 3: The number of orbitals in each case will be as follows:

1. When the Period 4 metal ion is forming a square planar complex, one 3d, one 4s and two 4p orbitals overlap to form four sp²d hybrid orbitals.

 example: ${\left[\text{Ni}{\left(\text{CN}\right)}_4\right]}^{2-}$

 

     (b)   When the Period 4 metal ion is forming octahedral complex, two 4d, one 4s and    three 4p orbitals overlap to form six sp²d hybrid orbitals.

example: ${\left[\text{Cr}{\left({\text{NH}}_3\right)}_6\right]}^{3+}$