Paramagnetism

Definition

Paramagnetism is a form of magnetism that occurs in materials with unpaired electrons, which causes them to be attracted to external magnetic fields. This phenomenon arises due to the alignment of the magnetic moments of the unpaired electrons with the applied field, resulting in a net magnetic moment in the material. Unlike diamagnetic materials, which are repelled by magnetic fields, paramagnetic substances exhibit a weak attraction, and this effect typically increases with temperature.

5 Must Know Facts For Your Next Test

1. Paramagnetic materials have at least one unpaired electron, which gives them a net magnetic moment.
2. The attraction to an external magnetic field in paramagnets is generally weak compared to ferromagnetic materials but stronger than in diamagnetic materials.
3. Examples of paramagnetic substances include oxygen (O2), iron(III) ions (Fe3+), and certain transition metal complexes.
4. As the temperature increases, thermal agitation can disrupt the alignment of magnetic moments, leading to decreased paramagnetic behavior.
5. When an external magnetic field is removed, paramagnetic materials lose their magnetization quickly because the thermal motion randomly reorients the unpaired electrons.

Review Questions

• How does the presence of unpaired electrons contribute to paramagnetism in materials?
  • The presence of unpaired electrons in a material is critical for its paramagnetic properties because these electrons possess intrinsic angular momentum and generate a magnetic moment. When an external magnetic field is applied, these unpaired electrons tend to align their magnetic moments with the field, resulting in an overall attraction towards the magnetic source. The degree of this alignment defines how strongly a material exhibits paramagnetism.
• Discuss how temperature affects the magnetic susceptibility of paramagnetic materials according to Curie Law.
  • According to Curie Law, the magnetic susceptibility of paramagnetic materials is inversely proportional to temperature. This means that as temperature increases, the thermal energy causes greater agitation among the unpaired electrons, disrupting their alignment with an external magnetic field. Consequently, this leads to a decrease in magnetic susceptibility and thus weaker paramagnetism at higher temperatures.
• Evaluate the significance of distinguishing between paramagnetism and diamagnetism when analyzing material properties in condensed matter physics.
  • Distinguishing between paramagnetism and diamagnetism is essential for understanding various material properties and their behaviors under external influences like magnetic fields. Paramagnetic materials can display significant interactions with magnetic fields due to their unpaired electrons, while diamagnetic materials exhibit negligible interactions that lead to repulsion. This differentiation helps physicists tailor materials for specific applications such as sensors and data storage technologies by manipulating their electronic structures and understanding their interactions at different temperatures.

Related terms

Unpaired Electrons: Electrons in an atom or molecule that are not paired with another electron in an orbital, contributing to the material's magnetic properties.

Magnetic Moment: A vector quantity that represents the strength and direction of a magnetic source, influenced by factors such as electron configuration.

Curie Law: A principle that describes how the magnetic susceptibility of paramagnetic materials varies inversely with temperature, indicating that paramagnetism decreases as temperature increases.