Discuss the magnetic properties of transition elements.

(N/A) In the presence of a magnetic field,two types of magnetic behaviour are observed for transition elements: $(i)$ Paramagnetism and $(ii)$ Diamagnetism. Paramagnetic substances are attracted by a magnetic field,while diamagnetic substances are repelled by the magnetic field.
Ferromagnetism is an extreme form of paramagnetism where the substance is very strongly attracted by the magnetic field. Paramagnetism arises from the presence of unpaired electrons in $(n-1)d$-orbitals,with each such electron having a magnetic moment associated with its spin as well as orbital motion. For most transition elements,the orbital contribution is not of much significance.
The magnetic moment expresses the paramagnetic behaviour of transition metal ions and is calculated using the "Spin-only" formula $\mu = \sqrt{n(n+2)} \ BM$,where:
$n =$ number of unpaired electrons in $(n-1)d$-orbitals
$\mu =$ Magnetic moment in Bohr Magneton $(BM)$

Ion	Configuration	Unpaired electron$(s)$	Calculated Magnetic moment	Observed Magnetic moment
$Sc^{3+}$	$3d^{0}$	$0$	$0$	$0$
$Ti^{3+}$	$3d^{1}$	$1$	$1.73$	$1.75$
$Ti^{2+}$	$3d^{2}$	$2$	$2.84$	$2.76$
$V^{2+}$	$3d^{3}$	$3$	$3.87$	$3.86$
$Cr^{2+}$	$3d^{4}$	$4$	$4.90$	$4.80$
$Mn^{2+}$	$3d^{5}$	$5$	$5.92$	$5.96$
$Fe^{2+}$	$3d^{6}$	$4$	$4.90$	$5.3-5.5$
$Co^{2+}$	$3d^{7}$	$3$	$3.87$	$4.4-5.2$
$Ni^{2+}$	$3d^{8}$	$2$	$2.84$	$2.9-3.4$
$Cu^{2+}$	$3d^{9}$	$1$	$1.73$	$1.8-2.2$
$Zn^{2+}$	$3d^{10}$	$0$	$0$	$-$

The magnetic moment increases with the increase in the number of unpaired electrons. If the magnetic moment is zero,the substance is diamagnetic and is repelled by the magnetic field.