Assertion : Magnetic moment of Dy is highest | vedclass

Name: PDF Generator App | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

In lanthanide ions the $4fe^-$ are well shielded from external field by the overlying $5s$ and $5p$ electrons. Thus the magnetic effect of the motion

Vedclass · Accepted Answer

If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.

Vedclass · Answer

In lanthanide ions the $4fe^-$ are well shielded from external field by the overlying $5s$ and $5p$ electrons. Thus the magnetic effect of the motion of the electron in its orbital is not quenched put, Thus the magnetic moment must be calculated taking into account both the magnetic momeent from unpaired $e^-$ spins and that from orbital motion.

$\mu \, = \,g\sqrt {J(J\, + \,1)} $

Where $g\, = \,1\frac{1}{2} + \,\frac{{S(S + 1)\, - \,L(L + 1)}}{{2J\,(J + 1)}}$

$J=L-S$ when the shell is less than half fill $=L+S$ when the shell is more than half fill.

In $Dy^{3+}\,([Xe]4f^9)$  $f-$ level is more than half fill hence spin and orbital motion work together, highest in lanthanoids.

Hence, both assertion and reason are true and reason is correct explanation of assertion.

Assertion : Magnetic moment of $Dy$ is highest among lanthanoids.

Reason : Orbital motion contributes magnetic moment.

Similar Questions

Ionisation enthalpies of $Ce,\,Pr$ and $Nd$ are higher than $Th,\,Pa$ and $U$. Why ?

The atomic radius of $Ag$ is closest to

Spin only magnetic moment of $\left[ MnBr _{6}\right]^{4-}$ is $.....\,B.M.$ (round off to the closest integer)

The purple colour of $KMnO_4$ is due to the transition

Explain the variations in atomic radii of transition elements along the period.

Assertion : Magnetic moment of $Dy$ is highest among lanthanoids. Reason : Orbital motion contributes magnetic moment.