Question

Explain the difference between a diamagnetic substance and a paramagnetic substance.

Short answer

The main differences between diamagnetic and paramagnetic substances are their electron configurations, magnetic moment alignments, and interactions with external magnetic fields. Diamagnetic substances have paired electrons with opposite spins, zero net magnetic moments, negative magnetic susceptibility, and are repelled by magnetic fields. Paramagnetic substances have unpaired electrons with parallel spins, net magnetic moments, positive magnetic susceptibility, and are attracted to magnetic fields. Additionally, the magnetic properties of paramagnetic substances are temperature-dependent, while those of diamagnetic substances are not.

Step-by-step solution

Definition of Diamagnetic Substance

A diamagnetic substance is a material that does not have any net magnetic moment of its own. When an external magnetic field is applied, it creates a magnetic field that opposes the applied field, resulting in a repulsive force. This is known as the Diamagnetic Effect. Examples of diamagnetic substances include copper, gold, and water.

Definition of Paramagnetic Substance

A paramagnetic substance is a material that has unpaired electrons which creates an intrinsic magnetic moment in each atom. When an external magnetic field is applied, these magnetic moments align themselves with the applied field, resulting in an attractive force. However, these magnetic moments are weak and transient, so the attraction is not strong. Examples of paramagnetic substances include aluminum, platinum, and oxygen.

Electron Spin Alignment

In diamagnetic substances, all electrons are paired, and their spins are opposite, which effectively cancels out their magnetic moments. On the other hand, paramagnetic substances have unpaired electrons with parallel spins, leading to a net magnetic moment.

Response to Applied Magnetic Field

Diamagnetic substances oppose the applied magnetic field, meaning that they are repelled by it. When exposed to a magnetic field, diamagnetic substances develop an induced magnetic field that is opposite to the applied field, resulting in a repulsive force. In contrast, paramagnetic substances are attracted to an applied magnetic field as their magnetic moments align with the applied field, creating an attractive force.

Magnetic Susceptibility

Magnetic susceptibility is a measure of how much a material is magnetized when an external magnetic field is applied. Diamagnetic materials have a negative magnetic susceptibility, meaning that they have an opposing magnetic field when an external magnetic field is present. Paramagnetic materials, on the other hand, have a positive magnetic susceptibility, meaning that they have an aligning magnetic field when an external magnetic field is present.

Temperature Dependence

The magnetic properties of diamagnetic substances do not change with temperature. In contrast, the magnetic properties of paramagnetic substances are temperature-dependent. Their magnetic susceptibility increases as the temperature decreases, according to Curie's Law. This is because the thermal motion of electrons is reduced, which helps stabilize the alignment of magnetic moments with the applied field. In conclusion, the main differences between diamagnetic and paramagnetic substances lie in their electron configurations, magnetic moment alignments, magnetic susceptibility, and the way they interact with external magnetic fields. Diamagnetic substances have paired electrons, zero net magnetic moments, and repel applied magnetic fields, while paramagnetic substances have unpaired electrons, net magnetic moments, and are attracted to applied magnetic fields.

Key concepts

Magnetic Susceptibility

When exploring magnetic properties, magnetic susceptibility is a key concept. It indicates how a material responds to an external magnetic field.
For diamagnetic substances, the magnetic susceptibility is negative, meaning they slightly repel the magnetic field.
This is a fascinating effect, as these materials generate an induced magnetic field opposite to the applied one. It's as if the material is saying, "No, thank you!" and gently pushing the field away. Paramagnetic substances, however, are more welcoming. They possess a positive magnetic susceptibility, signifying that they align with the magnetic field, albeit weakly.
These materials are thus slightly attracted to the field. It's important to note that while their response is generally stronger than diamagnetic materials, it is still quite weak compared to ferromagnetic materials like iron.
These variations stem from differences in electron configurations and how these electrons interact with external fields.

Electron Spin Alignment

Understanding electron spin alignment is crucial for grasping the differences between diamagnetic and paramagnetic substances.
In diamagnetic materials, all electrons are paired. This means their spins are aligned in opposite directions, canceling each other out. As a result, these materials exhibit no net magnetic moment under normal conditions.
It's like two children on a seesaw perfectly balancing each other out, resulting in no movement. In contrast, paramagnetic substances possess unpaired electrons.
These unpaired electrons have parallel spins, contributing to a small net magnetic moment. It's similar to having more children on one side of the seesaw, causing it to tilt in that direction.
This small but significant difference in electron spin arrangement defines the core magnetic behavior of these materials.

Temperature Dependence

Temperature plays a pivotal role in affecting the magnetic behavior of materials, particularly for paramagnetic substances. For diamagnetic materials, their magnetic properties remain stable irrespective of temperature changes. Whether cold or hot, these materials maintain their independence, gently repelling any external magnetic fields. Paramagnetic materials, however, are sensitive to temperature variations. According to Curie's Law, the magnetic susceptibility of paramagnetic substances increases as the temperature decreases. This is because lower temperatures reduce the thermal agitation of electrons, allowing their spins to align more easily in the presence of a magnetic field.
Consequently, these substances exhibit stronger magnetic properties at cooler temperatures. Understanding this temperature dependence is vital for applications that rely on magnetic materials.