Question

The spin only magnetic moment of $Fe^{3+}$ ion (in BM) is approximately:
(A). 4
(B). 7
(C). 5
(D). 6

Answer 1

Hint: Fe is the symbol of Iron metal. Iron metal belongs to the first transition series in the periodic table. Iron metal has a very large application on the Earth. When it is exposed in air, it forms iron oxide.

Complete step-by-step answer:

The magnetic strength and the orientation of any object that produces a magnetic field is known as a magnetic moment. Permanent magnets are the best example of objects having magnetic moments. Many astronomical objects like the Moon, stars have magnetic moments.
Atomic number of Iron is 26. It has 26 numbers of electrons and protons. The number of neutrons in Iron is 30. The inner and the outer core of Earth is formed by Iron. The most common metal in Earth’s crust by mass is Iron. The electronic configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{5}4s^{0}$. The number of unpaired electrons in $Fe^{3+}$ is 5.
The magnetic moment of $Fe^{3+}$ is,
$\mu =\sqrt{n\left ( n+2 \right )}$
Where, n = Number of unpaired electrons in $Fe^{3+}$
$\mu =\sqrt{5\left ( 5+2 \right )}$
$\mu =5.9 BM$
$\mu \approx 6 BM$
Correct option is D.

Note: The magnetic moment caused by the spin of elementary particles is the spin magnetic moment. Another type of the magnetic moment is the orbital magnetic moment of the particle. Both magnetic moments are different for single particles.