Problem 18 - Chemistry: The Central Science in SI Units, Global Edition

Question

Which type of magnetic material cannot be used to make permanent magnets, a ferromagnetic substance, an antiferromagnetic substance, or a ferrimagnetic substance?

Step-by-Step Solution

Answer

An antiferromagnetic substance cannot be used to make permanent magnets because it has a net magnetization of zero, resulting from the alignment of neighboring magnetic moments in opposite directions. Ferromagnetic and ferrimagnetic substances can form permanent magnets due to their strong attraction to magnetic fields and non-zero net magnetization.

Step 1: Understand the properties of ferromagnetic substances

A ferromagnetic substance is a material that has a strong attraction to magnetic fields. It can form permanent magnets when its magnetic domains are aligned in one direction. Examples of ferromagnetic materials include iron, nickel, and cobalt.

Step 2: Understand the properties of antiferromagnetic substances

An antiferromagnetic substance is a material in which neighboring magnetic moments (spins) align in opposite directions, resulting in a net magnetization of zero. These materials do not exhibit a strong attraction to magnetic fields and cannot form permanent magnets. Examples of antiferromagnetic materials include manganese oxide and chromates.

Step 3: Understand the properties of ferrimagnetic substances

A ferrimagnetic substance is a material in which neighboring magnetic moments (spins) align in opposite directions, but with different magnitudes. The net magnetization is non-zero, and these materials can exhibit strong attraction to magnetic fields and can form permanent magnets. Examples of ferrimagnetic materials include magnetite and some ferrites.

Step 4: Identify the magnetic material that cannot be used to make permanent magnets

Based on the properties of the three magnetic materials, we can conclude that an antiferromagnetic substance cannot be used to make permanent magnets, as its net magnetization is zero. Ferromagnetic and ferrimagnetic substances, on the other hand, can be used to make permanent magnets due to their strong attraction to magnetic fields and non-zero net magnetization.

Key Concepts

Ferromagnetic

Ferromagnetic materials have a unique property. They are strongly attracted to magnetic fields. This is due to their atomic structure, where their magnetic domains align in one direction. Now, what are magnetic domains? Think of them as tiny magnets within a substance. When many tiny magnets align in the same direction, they create a strong overall magnetic field.

You can find ferromagnetic materials in everyday objects, such as:

• Iron
• Nickel
• Cobalt

These materials are quite useful in making permanent magnets. This is because their aligned magnetic domains do not lose orientation easily. Thus, once magnetized, they retain their magnetism for a long time.

In summary, ferromagnetic substances are ideal for creating permanent magnets due to their strong attraction to magnets and ability to maintain their magnetic alignment.

Antiferromagnetic

Antiferromagnetic materials have an interesting feature where neighboring magnetic moments, or spins, align in opposite directions. This opposite alignment leads to a net magnetization of zero. In simpler terms, it's like two people pushing against each other with equal strength. The result? They don't move at all.

This zero net magnetization means that these materials do not exhibit a strong attraction to magnetic fields. Therefore, they cannot be used in making permanent magnets.

Common examples of antiferromagnetic materials include:

• Manganese oxide
• Chromates

Despite their lack of usefulness in permanent magnet creation, antiferromagnetic materials are significant in other areas, such as spintronics. Spintronics is a field that takes advantage of the electron's spin to store and process information.

Ferrimagnetic

Ferrimagnetic materials share some similarities with both ferromagnetic and antiferromagnetic substances. They have neighboring magnetic moments aligned in opposite directions, similar to antiferromagnetic materials. However, the magnitude of these moments is different, leading to a non-zero net magnetization.

Because of this, ferrimagnetic materials can exhibit a strong attraction to magnetic fields, making them capable of forming permanent magnets. They are used in applications where ferrites perform better than pure metals due to their electrical insulative properties.

Some typical ferrimagnetic materials include:

• Magnetite
• Some ferrites (used in transformers and inductors)

To sum up, ferrimagnetic substances, with their non-zero net magnetization, offer a combination of benefits for both electrical insulation and permanent magnet formation.