Which element is the best conductor of electricity?

In terms of the ability to conduct electricity, materials can be broadly divided into conducting, semiconducting, and insulating or dielectric materials. As its name implies, an electrical conductor is any material that is capable of conducting electricity when connected to a potential difference or when subjected to the action of an electric field.

The ability to conduct electricity is a characteristic property of metals. In fact, the vast majority of the best conductors are metallic elements. However, a very special allotrope of carbon is capable of competing with even the most conductive metal on the entire periodic table.

How is the ability of a material to conduct electricity measured?

The ability of a material to conduct electricity is measured by electrical conductivity. This is an intensive property of matter that represents the conductance of a conductor of unit length and cross section. Being an intensive property, it does not depend on the dimensions or the shape of the conductor but only on the material from which it is made. For this reason, if we want to compare elements based on their ability to conduct electricity, it is enough to compare their conductivities.

Depending on the conductivity of a material, it can be classified as a conductor, semiconductor, and insulator. The following table shows the conductivity ranges for each type of material:

Knowing what conductivity values ​​characterize conductors, the following table shows an ordered list of the conductivities of the 50 elements of the periodic table that best conduct electricity. These values ​​correspond to the conductivity of the elements in volume, that is, in macroscopic quantities.

As we can see, the element that best conducts electricity is silver (Ag) and has a conductivity of 6.30.10 ⁷ S/m . This means that a block of pure silver with a cross section of 1 m ² and a length of 1 m will have a conductivity of 6.30.10 ⁷ siemens or A/V. This, in turn, means that if we apply a constant electrical potential difference of 1 V between the two faces of the conductor, an electrical current of 6.30.10 ⁷ amps will be generated.

Conductivity expressed in this way is difficult to visualize, since it is not common to take a 1 m ³ block of pure silver and use it as an electrical conductor. Instead, it is more convenient to express conductivity in terms of Sm/mm ² . In these units, the conductivity of silver is 63.0 Sm/mm ² . This implies that if we apply a voltage of 1 V across a silver conductor that is 1 m long and has a cross-sectional area of ​​1 mm 2 , a current ^of 63.0 amperes will be generated.

Silver, copper, gold and aluminum as electrical conductors

A simple calculation from the data in the table above reveals that silver has a conductivity that is 5.7% higher than copper, 39.4% higher than gold , and 67.1% higher than aluminum. However, these three elements are used much more frequently in electrical applications than silver. In fact, silver is rarely used as an electrical conductor despite being the element that best conducts electricity.

The reasons behind this are simple. For one, copper is a much cheaper metal than silver, while being only slightly less conductive. For this reason, it makes much more sense to use copper in electronics and building wiring rather than silver, as the increase in conductivity does not justify the impressive increase in price.

This is even more true of aluminum, which is used even more frequently and in greater quantity than copper, especially in kilometer-long power lines. Aluminum is much cheaper and easier to produce than copper, and is also lighter and more resistant to corrosion. If we compare a copper conductor with an aluminum conductor with twice the cross-sectional area, the conductance of the aluminum conductor is more than twice that of the copper conductor (it conducts electricity better), its price is still lower (approximately one 40% cheaper) and, in addition, it is 40% lighter. All these characteristics make aluminum, despite ranking fourth in conductivity, a more suitable conductor than silver and copper in many applications.

On the other hand, gold is a much more expensive precious metal than silver, it is a worse electrical conductor, and it is much denser or heavier. It is worth asking ourselves, then, why is gold used more frequently as an electrical conductor than silver? The reason has to do with the chemical properties of gold. In addition to being a precious metal, gold is also a noble metal.very resistant to corrosion. This makes it the perfect material for manufacturing electrical contacts in applications such as computer equipment, mobile devices, etc. Silver, on the other hand, quickly acquires a patina on its surface when it comes into contact with air, due to the oxidation of the surface atoms. This reduces its conductivity making this metal unsuitable for this type of application.

Graphene is a better conductor than silver

If we talk about the conductivity of pure elements, there is one element that beats all the others and, curiously, it is not silver. It’s about carbon. However, we are not talking about just any carbon like the one we could find naturally, but about a very special form of carbon called graphene.

Graphene is a very particular allotrope of carbon. It is a hexagonal lattice of sp ² -hybridized carbon atoms one atom thick. It consists of only one of the layers of carbon atoms that make up the graphite allotrope. Being only one atom thick, this type of material is called a two-dimensional crystal and possesses unique physical properties, including the highest known electrical conductivity.

In some laboratories, conductivities of the order of 8.0.10 ⁷ S/m for graphene have been reported, which is 27% higher than the conductivity of silver, making graphene, and therefore carbon, the element that best conducts electricity .

Despite the above, the fact that this conductivity corresponds to nanometric samples of material instead of macroscopic volumes of the element, it may be inappropriate to compare this conductivity with that of other metals, which were measured for each element in macroscopic samples. . On this scale, some new form of another element may turn out to be a better conductor even than graphene. For this reason, for the moment, we can leave the gold medal to the silver.

References

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Pastor, J. (2014, February 7). Graphene conducts electricity even better than theory suggested . Xataka. https://www.xataka.com/investigacion/el-grafeno-conduce-la-electricidad-aun-mejor-de-lo-que-apuntaba-la-teoria

Rizwan, A. (2021, September 3). Why Silver is a Good Conductor of Electricity? Biomadam. https://www.biomadam.com/why-silver-is-good-conductor-of-electricity

Silver is the best conductor of heat and electricity.(a) True(b) False . (2020, August 14). Vedanthu. https://www.vedantu.com/question-answer/silver-is-the-best-conductor-of-heat-and-class-10-chemistry-cbse-5f363d6ff224761096d481fb

Why is silver the best conductor of electricity? (2016, November 16). Physics Stack Exchange. https://physics.stackexchange.com/questions/293019/why-is-silver-the-best-conductor-of-electricity