Paramagnetism

Definition

Paramagnetism is a form of magnetism that occurs in materials with unpaired electrons, resulting in a weak attraction to an external magnetic field. This phenomenon is due to the alignment of the magnetic moments of the unpaired electrons when subjected to a magnetic field, allowing paramagnetic materials to be attracted, albeit weakly, towards the source of the field. Unlike ferromagnetic materials, paramagnetic substances do not retain magnetization once the external field is removed.

5 Must Know Facts For Your Next Test

1. Paramagnetic materials have unpaired electrons that contribute to their magnetic properties, making them sensitive to external magnetic fields.
2. The attraction experienced by paramagnetic materials increases with stronger external magnetic fields, but this effect is relatively weak compared to ferromagnetic materials.
3. Common examples of paramagnetic substances include aluminum, platinum, and certain metal ions like iron(III) ions.
4. The paramagnetic effect disappears when the external magnetic field is removed, as there is no residual magnetization.
5. Temperature plays a significant role in paramagnetism; at higher temperatures, thermal agitation can disrupt the alignment of unpaired electrons, reducing the material's overall magnetic response.

Review Questions

• How does the presence of unpaired electrons contribute to the phenomenon of paramagnetism?
  • Unpaired electrons are crucial for paramagnetism because they create individual magnetic moments that can align with an external magnetic field. When a paramagnetic material is placed in such a field, these unpaired electrons tend to align their spins with the direction of the field, leading to a weak attraction. This behavior contrasts with diamagnetic materials, which lack unpaired electrons and do not exhibit attraction towards an external field.
• Compare and contrast paramagnetism and ferromagnetism in terms of material properties and behavior in magnetic fields.
  • Paramagnetism and ferromagnetism differ significantly in their material properties and responses to magnetic fields. While both types of materials have unpaired electrons that contribute to their magnetism, ferromagnetic materials can retain their magnetization even after the external field is removed due to the alignment of magnetic domains. In contrast, paramagnetic materials only exhibit magnetization in the presence of an external field and lose it immediately once the field is removed. Additionally, ferromagnetic materials experience strong attraction to magnets, while paramagnetic materials are attracted weakly.
• Evaluate how temperature affects the paramagnetic behavior of materials and its implications for practical applications.
  • Temperature significantly influences the paramagnetic behavior of materials because higher temperatures increase thermal agitation, which can disrupt the alignment of unpaired electrons. As a result, at elevated temperatures, the magnetic response of paramagnetic substances diminishes. This property has practical implications in applications like magnetic resonance imaging (MRI) and other technologies where controlling temperature can enhance or reduce the effectiveness of paramagnetic contrast agents.

Related terms

Diamagnetism: Diamagnetism is a form of magnetism observed in materials that do not have unpaired electrons, resulting in a very weak repulsion from an external magnetic field.

Ferromagnetism: Ferromagnetism is a strong form of magnetism exhibited by materials that can retain magnetic properties even after an external magnetic field is removed, due to the alignment of their magnetic domains.

Magnetic Moment: Magnetic moment is a vector quantity that represents the magnetic strength and orientation of a magnet or current-carrying loop, and is crucial in determining how materials respond to external magnetic fields.