Magnetic Properties Of Materials

The **magnetic moment** ( ) of an ion is an important property that is directly related to the number of unpaired electrons in the ion. It is calculated using the formula: where: is the number of unpaired electrons in the ion, is the Bohr magneton, a physical constant used to express magnetic moments.
Step 1: Determine the Electronic Configuration and Unpaired Electrons. We will now determine the electronic configuration and the number of unpaired electrons for the given ions: : Manganese (Mn) has an atomic number of 25. The neutral Mn configuration is . When it loses two electrons to become , the electron configuration becomes . Since all five electrons in the orbital are unpaired, the number of unpaired electrons . : Iron (Fe) has an atomic number of 26. The neutral Fe configuration is . When it loses three electrons to become , the configuration becomes . As with , all five electrons in the orbital are unpaired, so for as well. Step 2: Calculate the Magnetic Moment. Using the formula for the magnetic moment and substituting : Thus, both and have a magnetic moment of approximately .
Step 3: Conclusion. The elements and have the same magnetic moment because they both have 5 unpaired electrons. Therefore, the correct answer is .

Concept: Magnetic susceptibility ( ) is a measure of how much a material becomes magnetized in the presence of an external magnetic field. For paramagnetic materials, the susceptibility depends on temperature.

Step 1: Statement of Curie's Law. Curie's Law states that the magnetic susceptibility of a paramagnetic substance is inversely proportional to its absolute temperature. or where is Curie's constant and is the absolute temperature.

Step 2: Interpretation of the law.
• As temperature increases, thermal agitation increases.
• This reduces the alignment of magnetic dipoles.
• Hence, magnetic susceptibility decreases.

Step 3: Conclusion. Therefore, the law stating that magnetic susceptibility is inversely proportional to absolute temperature is Curie's Law.