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Is Mercury Magnetic? (Slightly Magnetic)

Is Mercury Magnetic? (Slightly Magnetic)

Mercury (Hg) is a chemical element with atomic number 80. It is a heavy, silvery d-block element and is the only metallic element that is liquid at standard temperature and pressure. Mercury is found in deposits throughout the world, mostly in the form of cinnabar (mercuric sulfide).

Have you ever wondered if mercury is magnetic? In this article, we are going to discuss just that. We will look at the properties and uses of the element. Then we will talk about the magnetic properties of mercury while also talking about a unique phenomenon known as cage diffusion. 

Is Mercury a Magnetic Material?

Yes, Mercury is slightly magnetic. It is a chemical element with the symbol Hg and atomic number 80. Mercury is a dense, silvery-white metal that is commonly used in thermometers, barometers, and other scientific instruments. While it is not strongly magnetic, it does exhibit some magnetic properties. When placed in a magnetic field, it becomes weakly magnetized in the direction of the field.

However, its magnetic properties are relatively weak compared to other magnetic metals, and it is not commonly used for magnetic applications.

Mercury is a weakly diamagnetic material at room temperature because it does not have unpaired electrons. However, physicists have recently discovered that liquid metals like mercury have magnetic moments that appear and disappear.

Let us first understand what magnetism is. Magnetism is a force caused by the motion of electric charges. Every substance is made up of atoms. These atoms have electrons (particles that carry an electric charge) that circle the atom’s center, called the nucleus.

In some substances like iron, the electrons spin in the same direction. This allows their magnetic fields to combine, and it produces a magnetic field extending beyond the atoms. These objects are strongly attracted to magnets and are called ferromagnetic. 

However, in most substances, equal numbers of electrons spin in opposite directions. This cancels out their magnetism, and they are not attracted to a magnetic field. These include things like cloth, wood, paper, etc., and are called diamagnetic.

Mercury’s electron configuration is [Xe] 4f145d106s2. All the orbitals are filled up to the 6s orbital, so mercury has a closed-shell electronic configuration. Since there are no unpaired electrons, mercury is diamagnetic.

However, Wouter Montfrooij and his colleagues at the University of Missouri have recently discovered that liquid metals that appear to be non-magnetic (such as mercury, aluminium, lead, etc.) actually exhibit short-lived magnetic moments.

In liquid substances, atoms approach each other very closely, which can often cause an electron to be ejected from a filled inner shell. As such, the atom has an unpaired electron, leading to a magnetic moment.

The shell fills up again once the ion moves away. This goes along with a process known as cage diffusion, by which an atom in a liquid bounces off a neighboring liquid and gets confined to a “cage”. The magnetic moment appears and disappears on the same time scale as the ion rattling around in the cage.

Is Frozen or Cold Mercury Magnetic?

Yes, frozen mercury is slightly magnetic. At room temperature, mercury is a weakly diamagnetic material that exhibits short-lived magnetic moments. However, it shows greater magnetism when the temperature is reduced. 

Since mercury does not have unpaired electrons, it behaves as a weak diamagnet at room temperature. However, at temperatures below 4° Kelvin (-269.15 °C or -452.47 °F), elemental mercury becomes a superconductor. 

The phenomenon of superconductivity itself was discovered by Heike Kamerlingh Onnes while studying mercury at low temperatures. Superconductors exhibit no magnetic resistance and expel magnetic flux fields. 

When a superconductor is placed in a magnetic field, it generates electric currents on its surface. These currents flow in such a way that they cancel out the external magnetic field inside the superconductor.

Therefore, the magnetic field is expelled from the superconductor. Since mercury becomes a superconductor at low temperatures, it also behaves in the same way, expelling magnetic fields. In other words, mercury becomes a perfect diamagnet at temperatures below 4 degrees Kelvin.

We can even make a permanent magnet with superconducting mercury. We just need to cool down a loop of mercury in a magnetic field. When the mercury becomes superconducting, the total magnetic flux will get locked through the loop.

If we switch off the external magnetic field, a persistent current will still flow down the mercury loop. It will essentially make a permanent magnetic field. This phenomenon is also known as the Meissner effect.

Is Liquid Mercury Magnetic?

Yes, liquid mercury is weakly magnetic. As mercury does not have unpaired electrons, it is a weakly diamagnetic material that repels a magnetic field. However, scientists have recently discovered that it exhibits brief magnetic moments.

Mercury’s electron configuration is [Xe] 4f145d106s2. All the orbitals are filled up to the 6s orbital, so mercury has a closed-shell electronic configuration. Since there are no unpaired electrons, mercury is diamagnetic. 

But scientists at the University of Missouri have recently discovered that liquid metals like mercury do exhibit short-lived magnetic moments. This happens along with a process known as cage diffusion.

In liquid metals, atoms are very close to each other, which can often cause an electron to be ejected from a filled inner shell. As such, the atom has an unpaired electron, leading to a magnetic moment.

Therefore, liquid mercury is magnetic at room temperature. The magnetism increases further when the temperature is reduced. 

Is Mercury Magnetic When Heated?

Yes, mercury is still weakly magnetic when heated. At room temperature, mercury is a diamagnetic material as it does not have unpaired electrons, although it does exhibit short-lived magnetic moments. When the temperature is heated, the diamagnetism increases.

Mercury does not have unpaired electrons, therefore it is a diamagnetic material that repels a magnetic field. However, the element does exhibit short-lived magnetic moments due to cage diffusion, as we discussed above.

When the temperature rises, the thermal energy makes the electrons in the mercury atoms move around more. This reduces their ability to align with the external magnetic field, which is required for magnetism. 

Therefore, when mercury is heated, it exhibits greater diamagnetism. 

How Strong is Mercury’s Magnetic Field?

Mercury has a weak magnetic field, and the magnetic susceptibility is also low. When brought to an external magnetic field, mercury weakly repels it, but the strength of this magnetization is quite low.

At room temperature, mercury is a weakly diamagnetic material as it does not have unpaired electrons. When exposed to an external magnetic field, mercury is weakly repelled.

Magnetic susceptibility is a measure of how much a material can be magnetized in the presence of an external magnetic field. In the case of mercury, this figure is quite low and is not typically measured in terms of magnetic field strength.

Uses of Mercury

These are the uses of mercury:

  1. Mercury is used in thermometers, barometers, and sphygmomanometers (blood pressure monitors). However, mercury is now largely being phased out from clinical environments due to worries about its toxicity. Now, alcohol- and galinstan-filled glass thermometers are replacing them. Similarly, mercury sphygmomanometers are being replaced by mechanical pressure gauges and electronic strain gauge sensors.
  2. It has several industrial applications. The mercury cell process (chlor-alkali) is used in the production of chlorine and caustic soda. Here, mercury is used as a cathode material to create sodium hydroxide and chlorine gas. But this process is also now being largely replaced by environment-friendly methods.
  3. The element is used in electrical appliances too, such as fluorescent lamps, mercury vapor lamps, and some types of batteries. In fluorescent lamps, electricity is passed through mercury vapor and it produces short-wave ultraviolet light. This then causes the phosphor in the tube to fluoresce, making visible light.
  4. Mercury and its compounds are used in dental fillings (known as amalgams) to fill cavities. But, again, this has now become controversial because of concerns about mercury vapor getting released from these fillings. Mercury is also used in small-scale gold mining operations to separate gold from other materials.
  5. Mercury is used in some food manufacturing processes. Mercuric chloride is used in the starch extraction process during rice, corn, and wheat refining, where it helps to inhibit starch-degrading enzymes.

As we can see, many of the uses of mercury are now being phased out due to its toxic nature and environmental concern. Most countries have implemented strict regulations on the use of mercury, and alternative technologies are being developed.

Properties of Mercury

These are the properties of mercury:

  • Having the atomic number 80, mercury is a silvery-white, dense, and liquid metal at room temperature. Mercury has a low melting point of -38.83°C, which is why it is liquid at room temperature.
  • Mercury is highly toxic. If ingested or inhaled, it can cause serious health problems, such as damage to the brain and nervous system. This is why many of its uses are now being replaced.
  • Mercury has a high density, which is about 13.5 times denser than water. This property makes it useful in barometers and manometers. Mercury also has a high thermal conductivity, which is why it is used in thermometers and thermostats
    .
  • Mercury has a high surface tension; it can form beads or droplets that can roll on surfaces. Electrical applications make use of this property.
  • Mercury is weakly diamagnetic, which means it is repelled by a magnetic field. However, scientists have recently discovered that it also exhibits short-lived magnetic moments.

Conclusion

In this article, we discussed the magnetic properties of mercury. Since mercury does not have unpaired electrons, it is a weakly diamagnetic substance at room temperature. But, because of cage diffusion, it exhibits brief magnetic moments. It also becomes a superconductor at low temperatures and acts as a perfect diamagnet. 

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