Silver is one of the seven metals of antiquity and have been considered precious throughout history. Silver coins, ornaments, utensils, jewellery and conductors have been popular since its discovery.
History and Discovery
Silver is a prehistoric metal and human have used silver as a primitive form of money along with gold and copper. Its exact discovery has not been known. The name silver is derived from Latin word argentum, that means “white” or “shiny”. Ornaments of silver have been found from ancient civilizations. In Egypt, silver was considered more precious than gold in the 15th century BC . Silver was predominantly present in form of ores, and various techniques were developed as early as in the 4th millennium BC, to extract pure silver. Greeks and Romans also used silver as currency. The rise of Athens was attributed to the nearby mines, which supplied about 30 tons of silver in 300 years (from 600 to 300 BC). Later, Romans became the biggest dealers of silvers and their economy circulated about ten times more silver than the combined amount of silver present in Europe in 800 AD. This trend continued until met a severe downfall with the fall of the Roman Empire. In Middle ages, Central Europe became the heart of silver mining and production. Around the 18th century, America was discovered and soon became the dominant producer of silver. But Spain and China remained the main collector of silver from throughout the world and the mines of the “New World” (America) supported the empire of Spain. But in the 19th century, North America, including Mexico, Canada and Nevada (US) took control over the production and are still the leading producers of silver, along with Peru.
Silver is quite abundant on Earth and is present in about 0.08 ppm in the Earth’s crust. It is predominantly present in the form of minerals and sulfide ores, such as argentite and acanthite. Silver is also present in salty water in the form of chlorargyrite (AgCl), which have high deposits in Wales and Chile. The principal source of silver are ores of lead, copper and lead-zinc. They are prevalent in China, Mexico, Australia and Peru . Currently, silver is produced as a secondary product in the refining of lead, copper and zinc. Silver mines are present in Australia, Poland, Bolivia, Mexico, china, Peru. Recently, one of the largest silver deposits in the world have been discovered in Tajikistan (Central Asia) .
Silver is a metallic white lustrous transition metal. It is very soft, malleable and ductile. Silver has the highest electrical conductivity among all metals. It also has exceptionally high thermal conductivity. And has the lowest contact resistant among all metals.
Silver is a fairly unreactive metal. it has the lowest first ionization energy in among Group 11 elements. It predominantly exists in oxidation state of +1, however, +2 and +3 states also exist. Compounds of silver have strong covalent characters. The electron affinity of silver is 125.6 kL/mol which is higher than hydrogen but lower than oxygen. Silver readily combines with zinc, gold and copper and form alloys. Silver forms organometallic compounds but they are quite unstable. Silver is resistant to reaction with air, even at higher temperatures. This property makes it a noel metal, like gold. It can react with sulfur compounds and forms a black tarnished silver sulfide. It readily dissolves in hot concentrated sulfuric acid, nitric acid and in aqueous cyanide solution.
Significance and Uses
- Silver is used in solar panels, water storage tanks, tableware, and utensils.
- Silver is widely used in electronic devices as conductors due to its high electrical conductivity.
- Silver is used as a colorant for making stained glass.
- Silver is used for brazing of various metals.
- Various compounds of silver are used in making of photographic and X-ray film.
- It is used in the manufacturing of window coatings and specialized mirrors.
- Silver is used as catalysis in various chemical reactions, such as oxidation relations.
- Silver is used in the manufacturing of wide range of chemical equipment as it has low chemical reactivity and is resistant to corrosion.
- Silver nitrate in dilute solution form, is used a common disinfectant and is present as antibiotic coating in catheters, bandages and other medical utensils.
- Nanoparticles of silver are widely used in for medicinal purposes as antifungal and antibacterial agents.
Silver compounds have low toxicity. Silver nitrate have caustic effect and can lead to tissue damage and diarrhea, low blood pressure and paralysis if ingested. Exposure and ingestion of large concentrations lead to accumulation of silver in the body, that lead to bluishness of skin and eyes. Some compounds of silver are highly combustible and require special precautions while handling, these include silver amide, silver oxide etc.
Isotopes of Silver
There are two stable isotopes in naturally occurring silver, silver-107 and solver -109. Both isotopes have almost the same abundance, i.e. silver-107 is 51 %, which is quite rare. There are 28 radioactive isotopes of silver .
. Weeks, pp. 14–19
. “Why Are Kyrgyzstan and Tajikistan So Split on Foreign Mining?”. EurasiaNet.org. 7 August 2013. Retrieved 19 August 2013.
. “Atomic Weights and Isotopic Compositions for All Elements (NIST)”. Retrieved 11 November 2009.