Paramagnetism

Definition

Paramagnetism is a form of magnetism that occurs in materials with unpaired electrons, causing them to be attracted to an external magnetic field. This property arises from the presence of unpaired electrons in the atomic or molecular structure of the substance, which results in a net magnetic moment. In paramagnetic materials, the magnetization is directly proportional to the applied magnetic field and disappears once the field is removed.

5 Must Know Facts For Your Next Test

1. Paramagnetic materials have unpaired electrons, which contribute to their magnetic properties and allow them to align with an external magnetic field.
2. The degree of paramagnetism is influenced by temperature; as temperature increases, thermal agitation can disrupt electron alignment, reducing magnetization.
3. Common examples of paramagnetic substances include aluminum, platinum, and certain metal ions such as iron(II) and manganese.
4. In contrast to ferromagnetic materials, paramagnetic materials do not retain magnetization once the external magnetic field is removed.
5. The behavior of paramagnetic materials can be described quantitatively using Curie's law, which states that the susceptibility of a paramagnetic material is inversely proportional to its temperature.

Review Questions

• How does the presence of unpaired electrons in paramagnetic materials influence their behavior in a magnetic field?
  • The presence of unpaired electrons in paramagnetic materials leads to the formation of a net magnetic moment, which makes them attracted to an external magnetic field. When exposed to this field, these unpaired electrons align their spins with it, resulting in magnetization. This alignment allows paramagnetic materials to exhibit a positive susceptibility to magnetic fields, meaning they become magnetized in the presence of an external field.
• Compare and contrast paramagnetism with diamagnetism and ferromagnetism in terms of electron configuration and response to external magnetic fields.
  • Paramagnetism occurs in materials with unpaired electrons, leading to a net magnetic moment and attraction to external magnetic fields. In contrast, diamagnetism occurs in materials with all paired electrons, resulting in a weak repulsion from magnetic fields. Ferromagnetism involves materials that can retain their magnetization due to strong interactions between adjacent atomic spins, often seen in iron. While paramagnetic and diamagnetic materials exhibit only temporary responses to fields, ferromagnetic materials can become permanently magnetized.
• Evaluate how temperature affects the paramagnetic properties of materials and relate this to Curie's law.
  • Temperature plays a crucial role in the paramagnetic properties of materials by influencing the thermal agitation of electrons. As temperature increases, the increased thermal motion can disrupt the alignment of unpaired electrons with an external magnetic field, decreasing the overall magnetization. This relationship is quantitatively expressed by Curie's law, which states that the magnetic susceptibility of a paramagnetic material is inversely proportional to its temperature. Therefore, as temperature rises, susceptibility decreases, demonstrating how thermal energy competes with magnetic alignment.

Related terms

Ferromagnetism: A type of magnetism where certain materials can become permanently magnetized due to the alignment of their magnetic moments.

Diamagnetism:

A form of magnetism that occurs in materials where all electrons are paired, leading to a very weak repulsion from a magnetic field.

Magnetic Moment: A vector quantity that represents the strength and direction of a magnetic source, related to the arrangement of electrons within atoms.