Question

Which of the following ions has the highest magnetic moment?

• A. Zn\(^{2+}\)
• B. Ti\(^{3+}\)
• C. Sc\(^{3+}\)
• D. Mn\(^{2+}\)

Hint:

Magnetic moment order: Mn\(^{2+}\) (5 unpaired) > Ti\(^{3+}\) (1 unpaired) > Zn\(^{2+}\)/Sc\(^{3+}\) (0 unpaired).

Answer 1

The Correct Option is D

To determine which ion has the highest magnetic moment, we must consider the number of unpaired electrons in the given ions. The magnetic moment of an ion is directly related to the number of unpaired electrons it has. This can be calculated using the formula:

\(\mu = \sqrt{n(n+2)}\)

where n is the number of unpaired electrons.

1. Zn\(^{2+}\): Zinc (Zn) has an atomic number of 30, and its electronic configuration in the ground state is [Ar] 3d^{10} 4s^{0}. When Zn loses 2 electrons to form Zn\(^{2+}\), it loses electrons from the 4s orbital, resulting in [Ar] 3d^{10}. There are no unpaired electrons, so n = 0. Hence, the magnetic moment is zero.
2. Ti\(^{3+}\): Titanium (Ti) has an atomic number of 22, with a ground state electronic configuration of [Ar] 3d^{2} 4s^{2}. For Ti\(^{3+}\), it loses three electrons, resulting in a configuration of [Ar] 3d^{1}. There is 1 unpaired electron, so n = 1. The magnetic moment is \(\mu = \sqrt{1(1+2)} = \sqrt{3} \approx 1.73\).
3. Sc\(^{3+}\): Scandium (Sc) has an atomic number of 21, with a ground state configuration of [Ar] 3d^{1} 4s^{2}. For Sc\(^{3+}\), all three electrons from the 4s and 3d orbitals are removed, resulting in [Ar]. There are no unpaired electrons, so n = 0. The magnetic moment is zero.
4. Mn\(^{2+}\): Manganese (Mn) has an atomic number of 25, with a ground state configuration of [Ar] 3d^{5} 4s^{2}. For Mn\(^{2+}\), two electrons are removed from the 4s orbital, resulting in [Ar] 3d^{5}. There are 5 unpaired electrons, so n = 5. The magnetic moment is \(\mu = \sqrt{5(5+2)} = \sqrt{35} \approx 5.92\).

Among the given ions, Mn\(^{2+}\) has the highest magnetic moment because it has the maximum number of unpaired electrons (5). Thus, the correct answer is Mn\(^{2+}\).