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. and that of Co 2+ is 4.87 B.M. Why?

Question

Philoid · Accepted Answer

The electronic configuration of

Cr³⁺ - [Ar] 3d³

Co²⁺- [Ar] 3d⁷

Cr³⁺ has a symmetrical electron distribution and will only have spin magnetic moment contribution whereas Co²⁺ has no symmetrical distribution of electrons so it will have orbital magnetic moment and spin magnetic moment contribution. Therefore, the total magnetic moment for Co²⁺ will be higher than Cr³⁺.

Although Cr3+ and Co2+ ions have same number of unpaired electrons but the magnetic moment of Cr3+ is 3.87 B.M. and that of Co2+ is 4.87 B.M. Why?

Although Cr³⁺ and Co²⁺ ions have same number of unpaired electrons but the magnetic moment of Cr³⁺ is 3.87 B.M. and that of Co²⁺ is 4.87 B.M. Why?