Question

Magnetic moment of a first-row transition-metal complex M (H,o), is 3.9 Bohr magnetons. Identify the metal

Answer 1

Correct Question :-  

Magnetic moment of a first-row transition-metal complex [M (H₂O)₆]²⁺ is 3.9 BM . Identify the metal .

Answer :-

The metal is Cobalt (Co) .

- Given Magnetic moment = 3.9 BM

- But we know that magnetic moment = √n(n+2)

- So ,√n(n+2) = 3.9

         n (n+2) = 15.21

                  n = 3

- Thus the no of unpaired electrons in the given metal is 3 .

- The metal of first transition series which forms [M (H₂O)₆]²⁺ with 3 unpaired electrons is Cobalt (27) .

- In +2 oxidation state , there are 7 electrons in the d sub-shell of cobalt .

- As H₂O is a weak field compound , so it does not pair up the d electrons .

- so in d sub-shell of cobalt, 2 electron pairs are formed and 3 electrons remain unpaired.