Question

Although Cr^3+ and Co^2+ ions have same number of unpaired electrons but the magnetic moment of Cr^3+ is 3.87 B.M.

Answer 1

Due to symmetrical electronic configuration there is no orbital contribution in Cr3+ ion. However appreciable orbital contribution takes place in Co2+ ion.

Answer 2

Hey dear,

● Explaination -
1) For Cr3+,
No of free electrons = 3
Spin only magnetic moment
SMM = √(3×5) = 3.87 BM

Orbital magnetic moment, rarely plays role here.
OMM = 0

Therefore,
Total magnetic moment = 3.87 + 0 = 3.87 BM

2) For Co2+,
No of free electrons = 3
Spin only magnetic moment
SMM = √(3×5) = 3.87 BM

Orbital magnetic moment is significant in this case.
OMM = 1

Therefore,
Total magnetic moment = 3.87 + 1 = 4.87 BM

Hope this helps you...