Most metals conduct electricity and heat, but some are much better than others. “Conductivity” measures the amount of electrical current or heat that can pass through a material.
From an atomic perspective, the most conductive materials have one highly active electron on the atom’s outer shell (the valence electron).
The metallic bond is the force of constantly moving electrons that holds the atom together. It is responsible for the high electrical and thermal conductivity properties, luster and malleability. Combined, these properties define the most conductive metals.
Most conductive metals
Not all metals have the same level of conductivity – here are five of the most conductive:
- Silver (Ag) is the most conductive metal on earth, with only one valence electron. Since it is more expensive than most metals, it is typically used on specialized equipment, jewelry and as a tangible investment asset. It’s also found in computers, photography, mirrors, cutlery, water filters and solar panels.
- Copper (Cu) has only one valence electron but is less conductive than silver. It is cheaper than silver and is often found in wiring, plating, household appliances and wrapping electromagnetic cores. Copper is easily machined and commonly used in marine applications because of its natural corrosion resistance and antimicrobial properties. It is a soft and malleable metal that forms a patina over time with exposure to moisture.
- Gold (Au) is best known for its use in jewelry and as a valuable and highly traded commodity as a hedge against a weak economy. The metal itself is soft and malleable and used in electronics as well as decoration on glassware. Gold injections were once used to treat rheumatoid arthritis, but this is no longer the case due to concerns over toxicity levels. Just like copper and silver, gold also has only one valence electron and demonstrates good conductivity.
- Aluminum (Al) is a light but strong metal that is often used, second only to iron. Although it has three valence electrons, it serves as a good conductor. Various castings, structures and commercial products make use of this material. Aluminum is also used in packaging and to encase high voltage transmission lines. This metal forms an oxide surface that is electrically resistant over time and may cause the connection to overheat. Aluminum is heavily recycled.
- Zinc (Zn) is a blue-grey metal that is brittle at room temperature but becomes malleable at 100°C. It is a moderate conductor of electricity. Die casting, pennies (USA), galvanizing iron as well as a pigment in paint and cosmetics all make use of this material. The beauty industry uses in trace amounts as a health supplement for premature aging. Like aluminum, zinc is highly recyclable.
Determining metal conductivity
There are several factors that influence the conductivity of a metal including:
- Impurities in the material that can hinder electron flow and decrease conductivity.
- Changes in temperature alter connectivity. Warmth excites the atoms, decreases conductivity and increases resistance; it is a linear relationship until you reach low temperatures.
- Frequency impacts conductivity as higher frequencies cause current to flow around the conductor rather than through it.
- Material phases/crystalline structure can impact conductivity if there are different material phases. It also depends upon how the material has been processed.
- Electro-magnetic fields are generated when electricity passes through the material. These fields are perpendicular to the electric flow and produce magnetoresistance, slowing the flow of electrical current.