Conductivity is a material’s ability to transmit energy. Because there are different forms of energy, there are different types of conductivity, including electrical, thermal, and acoustic conductivity. Silver is the most conductive element, in terms of electrical conductivity. Carbon in the form of diamond is the best thermal conductor (silver is the best metal). After silver, copper is the next best conductor, followed by gold. In general, metals are the best thermal and electrical conductors.
Why Is Silver the Best Conductor?
The reason silver is the best electrical conductor is because its electrons are freer to move than those of other elements. This has to do with silver’s crystal structure and electron configuration. Although silver is the best electrical conductor, it readily tarnishes and loses conductivity, plus it is more expensive than copper. Gold is used when corrosion resistance is important.
Electrical Conductivity of the Elements
Here is a table of the electrical conductivity of the ten most conductive elements. All of these elements are metals. Many alloys are also conductive, including carbon steel, stainless steel, brass, bronze, Galinstan, and Manganin. Nonmetals are electrical insulators, with a few exceptions.
| Element | Conductivity (S/m at 20°C) |
| Silver | 6.30×107 |
| Copper | 5.96×107 |
| Gold | 4.11×107 |
| Aluminum | 3.77×107 |
| Calcium | 2.98×107 |
| Tungsten | 1.79×107 |
| Zinc | 1.69×107 |
| Cobalt | 1.60×107 |
| Nickel | 1.43×107 |
| Ruthenium | 1.41×107 |
Thermal Conductivity of the Elements
Here is a table of thermal conductivity of the elements. Most tables only list metals, because metals in general conduct heat better than nonmetals. Diamond (a nonmetal) is an exception.
| Element | Thermal Conductivity (W/cmK) |
| Diamond (carbon) | 8.95 to 13.50 |
| Silver | 4.29 |
| Copper | 4.01 |
| Gold | 3.17 |
| Aluminum | 2.37 |
| Beryllium | 2.01 |
| Calcium | 2.01 |
| Tungsten | 1.74 |
| Magnesium | 1.56 |
| Rhodium | 1.5 |
| Silicon | 1.48 |
Do Any Nonmetals Conduct?
While the best conductors are metals, some nonmetals do conduct heat and electricity. Diamond (crystalline carbon) is an excellent thermal conductor, although it is an electrical insulator. However, amorphous carbon and graphite do conduct electricity. Semimetals are fair conductors. Germanium and silicon do not conduct electricity as well as graphite, but they are more conductive than sea water.
Factors That Affect Electrical Conductivity
Several factors influence electrical conductivity:
- Temperature: Tables of electrical conductivity include temperature because increasing temperature thermally excites atoms and decreases conductivity (increases resistivity). Overall, the relationship between temperature and conductivity is linear, but it breaks down at low temperatures.
- Size and Shape: Electrical resistance is proportional to length and inversely proportional to cross-sectional area. Charge flows at a higher rate through shorter wires and those with a greater cross-sectional area.
- Purity: Adding an impurity to a conductor decreases electrical conductivity. Meanwhile, doping a semiconductor may increase its conductivity. Tarnished silver is not as good a conductor as clean silver. Silicon doped with phosphorus becomes an N-type semiconductor, while silicon doped with boron becomes a P-type semiconductor.
- Crystal structure: The crystal structure of an element affects its conductivity. Diamond and graphite are both crystalline forms of carbon. Diamond is an electrical insulator, while graphite conducts electricity.
- Phases: Different phases may be present, even in a pure sample. Phase interfaces typically slow conductivity. So, the way a material is produced affects its conductivity.
- Electromagnetic fields: External electromagnetic fields may produce magnetoresistance within an electrical conductor. Also, when current passes through a conductor, it generates a magnetic field. The magnetic field is perpendicular to the electrical field.
- Frequency: Frequency is the number of oscillation cycles of an alternative electrical current. Above a certain frequency, current flows around a conductor rather than through it. This is called the skin effect. Skin effect does not occur with direct current because there is no oscillation and thus no frequency.
References
- Bird, R. Byron; Stewart, Warren E.; Lightfoot, Edwin N. (2007). Transport Phenomena (2nd ed.). John Wiley & Sons, Inc. ISBN 978-0-470-11539-8.
- Holman, J.P. (1997). Heat Transfer (8th ed.). McGraw Hill. ISBN 0-07-844785-28.
- Matula, R.A. (1979). “Electrical resistivity of copper, gold, palladium, and silver.” Journal of Physical and Chemical Reference Data. 8 (4): 1147. doi:10.1063/1.555614
- Serway, Raymond A. (1998). Principles of Physics (2nd ed.). Fort Worth, Texas; London: Saunders College Pub. ISBN 978-0-03-020457-9.
- “Thermal Conductivity of Elements.” Angstom Sciences.