Physical and chemical properties of silver

Silver (argentum, meaning white in Latin, symbol Ag) has excellent chemical and electrical properties, it is malleable but hard. Due to its lower melting point (961.78 °C) it is processed better than gold.

It rarely occurs in nature in pure form, usually it is bound with copper, lead, zinc and gold. Nearly 150 silver minerals are known.

Silver’s exceptional properties predestined it for wide use and high demand.

The hardness of silver on a scale from 1 to 10 (where 1 represents the softest substances, such as talc, graphite or lead, and 10 is diamonds) is similarly to gold, i.e. about 2.5 to 3, which is the hardness between the rock salt and copper.

The density of admixtures in silver reaches 9.6–12 g/cm³, which is about two times less than gold. Compared to gold, therefore, silver is larger in volume.

Malleability. One kilogram of silver can be pulled into a 2 km long wire, which is so flexible and ductile that jewellery with a great level of detail can be made of it. It can even be used to create thread, which is currently widely used in the textile industry.

Conductivity Silver has the highest thermal and electrical conductivity of all metals, so it is irreplaceable by other metals. It is used in various industries such as electronics, solar energy, electricity, etc. Silver has also found a new use in silver-zinc batteries, which may in the near future completely replace today’s massively widespread lithium-ion batteries.

Antibacterial effects. Already in the Middle Ages, people began to make silverware because they discovered its propensity to kill bacteria. Another known feature of silver is that it “enlivens” water. Silver immersed in water causes a weak chemical reaction, thereby creating antibacterial effects and so disinfecting water. These effects of silver were confirmed during the campaigns of Alexander of Macedonia, and so-called holy water was obtained from silver vessels in the Middle Ages. Enlivening water with silver is still carried out today using silver electrodes between which an electric current flows.

In medicine, this unique feature of silver is used by adding silver to medicines. The most well-known modern application is so-called colloidal silver, which are microparticles of silver that circulate in the body and are able to “eliminate” up to 100 times more pathogenic bacteria than antibiotics.

Reflectance. This other unique feature of silver has opened up use, for example, in the manufacture of mirrors or solar panels.

Silver darkens with the effect of light. Without this feature of silver, neither photography nor film would have been invented. Photographic film is actually plastic coated with an emulsion with light-sensitive silver halide crystals of different sizes. When expos  ed to a certain amount of light, an invisible image is formed which is developed using chemicals. Colour film is made by adding dye to these crystals. Apparently, that’s why movie projection screens are called the “silver screen”.

Most recently, this feature is used in optics – the well-known halogen (darkening) glass is made with the addition of silver, which darkens in the sun and fades in shadow.

Sonority. Another hidden feature of silver is the sound it emits on impact. The silver bell is the symbol of a clear bright sound. That is why silver is also added to bell metal, and why some stringed instruments have strings containing up to 78% of silver.

The production of silver is most often carried out by the cyanide leaching of silver ores; in the past, the amalgam process was also used, or silver was leached from the ore using thiosulfate solutions. Silver was refined with electrolysis using an acidified silver nitrate solution as the electrolyte. Waste anode sludge after the electrolytic refining of silver is a source of gold.