Silver is a soft, malleable metal with a characteristic sheen. It has the highest thermal and electrical conductivities of all metals. It is generally found pure, or in sulphide or arsenide ores. The pure metal is stable to water and oxygen, however when it comes in touch with sulphur in the air it creates the characteristic black layer of silver sulphide. It is soluble in sulphuric and nitric acids. Some silver salts are sensitive to light and are key in the silver gelatine process in photography. Other applications and industries in which silver is used include the manufacture of jewellery (both as the pure metal and combined into different alloys), the electrical industry and for the silvering of glass. Throughout history, silver has also been used in coin making, adornments, mirrors and photo-optics, musical instruments, dentistry and medicine. Because of its high conductivity and resistance to heat, silver is often used for contact points in electrical and motor control switches. High quality speaker systems may use silver wires for their magnet wire to achieve optimum sound.
Silver is also known for its reflectivity – when polished, silver becomes the most reflective surface on Earth. It is so reflective it is used in the making of crystalline solar panels. Nuclear energy also uses silver. It is often employed in control rods to capture neutrons and slow the rate of fission in nuclear reactors. Inserting the control rods into the nuclear core slows the reaction, while removing them speeds it up. Silver can also be used to prevent the growth of bacteria and can replace other bacteria-preventing chemicals like chlorine in water filters, water purifiers, swimming pools, and even clothes.
Silver applications are continually being explored. Silver is one of many options for replacing toxic chromated copper arsenate as a wood preservative. Nanosilver is being used in inks and coatings for paper and other surfaces. Silver metal glass, produced by cooling silver quickly, offers durable strength that resists deformation. Silver-based ionic liquids, which are in a liquid state at room temperature, can be used to clean up petroleum waste products. Silver in fabric allows touch screen users to keep their gloves on during cold weather.
Although silver’s thermal and electrical conductivity is extremely effective, it is also very expensive. As a result, cheaper metals like copper are often used with a silver coating. This way, conductivity is increased at a much cheaper cost. Silver coated wires are used in areas of science that require the best quality of conductivity, such as radio frequency engineering.