Quick fact file: Silver
Atomic number: 47
Atomic weight: 107.9
Melting point : 960.5 degrees C
Specific gravity: 10.5 when pure
Hardness: 2.5 – 3
Silver is more plentiful than gold, and shares many of the same remarkable properties.
What is silver?
Silver is a ductile, malleable, brilliant greyish-white metal.
The chemical symbol for silver is Ag, meaning ‘argentum’ – an ancient or poetic word for silver. The term ‘sterling’ denotes a specific weight of silver. This has come to be a term meaning ‘excellence’.
The price of silver and other precious metals is quoted in terms of troy ounces. The term ‘troy’ is derived from Troyes, France, a major trading city of the Middle Ages. One troy ounce equals 31.1 grams.
What is What are the properties of silver?
Silver has the highest electrical and thermal conductivity of any metal. It is malleable (easily shaped), ductile (can be drawn into very thin wire) and has antiseptic properties.
Where is silver found?
Silver is found as a free metal in nature or bound up with rock and too small to see with the naked eye. It is often, but not always, found in association with gold or other metals. The Martha and Favona mines are the only current producers of silver in New Zealand. The metal particles are mixed with the rock and too small to be seen. 75 – 90% of the precious metal produced in Waihi is silver.
What has silver been used for in the past?
Silver has had many practical and artistic uses. Because it was found as a free metal and was easy to work it was put to a variety of uses. The early discovery that water, wine, milk and vinegar stayed pure longer in silver vessels, led to its use as a container for long voyages on land and sea over 2,500 years ago.
Silver uses today
The many properties of silver mean that it is widely used today in science and technology. Each year over 7,000 new patents and papers are published which describe a product or process in which silver is a vital part.
Silver has a range of specialised electrical, mechanical, optical and medicinal properties. Silver is used in solar panels and spacecraft, plumbing and pendants. It has not been an easy metal to replace as new technology reveals additional applications.
The photographic industry uses a large percentage of the silver used each year throughout the world. Silver halides, coupled with dyes produce colour photographic images. X-Ray and black and white photography also rely on silver.
Watches, cameras and calculators use silver in their batteries to provide higher voltage and longer life. Silver oxide-zinc batteries, which have twice the electrical capacity of lead-acid batteries of the same size, are used extensively in aircraft and submarines, where weight is critical.
Silver concentrates the sun’s rays on solar collectors. It is found on the backs of mirrors and protects the heat-reflecting gold film on windows. Under the keys of almost every personal computer is a panel of switches with silver contacts to carry out the countless millions of instructions.
Silver thiosulphate prevents the release of ethylene gas from cut flowers to produce longer lasting blooms destined for export. Silver can be prepared as crystals of silver iodine and seeded into cold cloud to produce raindrops or snowflakes.
Around the home
Water filters used to purify swimming pool and drinking water use silver to prevent the build-up of bacteria and algae.
Microwave cooking is made more appetising due to a silver alloy coating applied to the bottom of microwave cookware. The surface of the cookware will reach a high temperature quickly, resulting in a browning or crisping of food surfaces.
We use the term ‘silverware’ to indicate the best cutlery. Many of the best table accessories such as knives, forks and spoons; jugs, serving dishes and trays are made out of silver.
Silver—and gold—are used in the treatment of arthritis where gold can be injected into muscles, and silver is used to coat arthritis pills.
Burns are disinfected with silver creams and bones are mended with cement containing antibacterial silver salts. Silver is combined with the powerful chemotherapeutic agent sulphadiazine to produce a drug 50 times more powerful than sulphadiazine alone. It is the most widely used drug for treating burn wounds.
Silver is also widely used in dentistry. Silver nitrate can be administered to new-born infants’ eyes to eliminate the incidence of Gonococcal Ophthalmia, a disease which can cause blindness.