Silver

Silver is the most electrically conductive metal in the world, better even than copper. It has been prized for millennia for its beauty, used in coins for 2,500 years, and its compounds defined photography for 150 years. Today it is increasingly important in solar panels, electronics and medical wound dressings.

• Atomic Number4747 protons, 47 electrons
• Atomic Mass107.868 u47× heavier than hydrogen
• State at Room TempSolidSolid
• Density10.501 g/cm³
• Melting / Boiling961.8°C / 2161.8°C
• DiscoveredAncient

What is Silver?

Silver is a transition metal in Group 11 of the periodic table, sitting below copper and above gold. With 47 protons and 61 common oxidation state of +1, it forms colourless or pale yellow salts. Silver is the best conductor of electricity of any element, the best conductor of heat, and is among the most reflective metals. Pure silver is soft and is usually alloyed with copper (sterling silver is 92.5% silver) for durability.

Silver's English name comes from the Old English word seolfor, related to similar words in other Germanic languages. The chemical symbol Ag comes from the Latin argentum and the Greek argyros, both meaning silver. The country Argentina takes its name from silver, Spanish explorers hoped to find silver there (they were disappointed). Silver has been known and worked by humans for at least 5,000 years.

Fact Silver is the best conductor of electricity of any material, better than copper, gold or any other element. Yet copper is used for most electrical wiring because it costs far less. Silver is reserved for applications where the highest possible conductivity is worth the extra cost, such as premium audio cables, high-frequency electronics and some aerospace applications.

Where you find Silver

In space

Silver is produced in stellar explosions called neutron star mergers. Our Sun contains silver. Scientists confirmed in 2017 that the collision of two neutron stars (detected as gravitational wave event GW170817) produced enormous quantities of silver, gold and other heavy elements.

On Earth

Silver is relatively rare in the Earth's crust at approx. 0.07 parts per million, but has been mined for 5,000 years because it sometimes occurs as native metal.

• Native silver. Pure silver nuggets and wire occur in some deposits, particularly in Germany, Norway, Canada and Mexico, where silver veins were formed by hydrothermal fluids.
• Silver ores. The main ores are argentite (silver sulfide, Ag₂S) and horn silver (silver chloride, AgCl), found in many countries. Mexico, Peru, China and Russia are the largest producers.
• By-product of lead and copper mining. Most silver is now recovered as a by-product of smelting lead, zinc and copper ores.

How we use Silver

• Photography (historically).. Silver halides (AgBr, AgCl, AgI) are light-sensitive. For 150 years from 1839, film photography depended on these compounds capturing images. Digital photography has largely replaced film, but silver is still used in some specialist photographic papers.
• Solar panels.. Silver paste is screen-printed onto solar cells as electrical contacts. A typical solar panel contains approx. 20 grams of silver. Growing solar panel production is a major driver of silver demand.
• Electronics.. Silver is used in switches, contacts and conductive pastes in electronic circuits. Every time you turn on a light switch, you are using a silver contact.
• Antimicrobial uses.. Silver ions kill bacteria and are incorporated into wound dressings, catheters and coatings on surgical instruments to prevent infection. Colloidal silver preparations have been used medicinally for centuries.

Did you know? The story that the Great Wall of China is visible from space is a myth, but another silver connection to space is real: the visors of astronauts' helmets are coated with a thin film of gold (not silver), but early space suits used silver cooling tubes. The first photographs taken on the Moon were captured on silver halide film carried by the Apollo astronauts.

How it was discovered

Silver has been known since prehistoric times, silver ornaments have been found in pre-Dynastic Egypt dating to around 3500 BCE. Silver mining was important in ancient Greece (the Laurion mines funded Athens's fleet and culture). The Romans mined silver extensively. It was one of the seven metals known to antiquity alongside gold, copper, iron, mercury, tin and lead.

Deeper dive: silver chemistry and applications

Silver's antimicrobial properties arise from silver ions (Ag⁺), which bind to bacterial cell walls and membranes, disrupting their function and killing the bacteria. Unlike antibiotics, bacteria have difficulty developing resistance to silver ions because silver attacks multiple molecular targets simultaneously. Silver wound dressings, incorporating silver nanoparticles or silver sulfadiazine, are used in treating burns and chronic wounds, where infection prevention is critical.

The Comstock Lode in Nevada, discovered in 1859, was one of the richest silver deposits ever found. The silver it produced financed the American Civil War from the Union side and helped fund the industrialisation of San Francisco. The Latin American silver mines, particularly at Potosí in Bolivia, supplied the Spanish empire with enormous wealth for 300 years and drove the development of global trade networks in the 16th and 17th centuries.

Moving to 48 protons on the periodic table brings us to Cadmium.