Saved Bookmarks
| 1. |
Assertion : Magnetic moment of Dy is the highest among langthanoids. Reason : Orbital motion contributes magnetic moment. |
|
Answer» If both assertion and reason are true and reason is the correct explanation of assertion `mu_(S+L)=sqrt(4S(S+1)+L(L+1))` S = resultant SPIN quantum number L = resultant orbital momentum quantum number `mu = g sqrt(J(J+1))` where `g=(3)/(2)+(S(S+1)-L(L+1))/(2J(J+1))` we know, J = L - S when the shell is less than half full. J = L + S when it is more than half full. Electronic configuration of `Dy=[Xe]4f^(10)6s^(2)` `Dy^(3+)=[Xe]4f^(9)`  Here S = 5/2 (since there are five unpaired electron) `L = -1xx1+0xx1+1xx1+2xx1+3xx1=5` So, `J =L+S=15//2` Now, `g=(3)/(2)+(35//4-30)/(2xx(15)/(2)xx(17)/(2))=1.334` `mu = g sqrt(J+(J+1))=10.65 BM` Thus calculated VALUE of magnetic moment of Dy is the highest among the LANTHANOID. |
|