Introduction
Silver is a precious metal present in group number 11 of the periodic table. Its atomic number is 47 whereas its atomic mass is 107.86. It has 47 electrons. Silver has 47 protons and 60 neutrons in its nucleus. Its scientific name is Argentum. Silver is represented by the symbol “Ag”.
Naming and History
The name silver is from the Anglo-Saxon word “Seolfor”. However, its scientific name “Argentum” is derived from the Latin word which means silver. It is in turn derived from the Sanskrit word “Argunas” which means shining.
Silver is known to man since prehistoric times. Slag heaps in Anatolia in Turkey and Greece showed that silver mining is dated as long as 3000 B.C. The silver artifacts have been found in the Sumerian city.
People of that time obtained it through the process called cupellation; the method invented by the Chaldeans. First, the ore was smelted, then cupellation of metals was done i.e., metals were heated up to 1000 C in a strong stream of air.
As a result, lead reacted with oxygen to form a lead oxide, leaving behind the liquid silver metal.
Silver is linked with money for a very long. In at least 14 languages such as in French word “Argent” is used for silver and the same for money. Similarly, Romans used the “Argentarius” word for silver, which they also used for the banker.
Occurrence of Silver
Silver is one of the rare elements on Earth’s crust. It can be found free as well as in combined form with other metals or elements. It can exist in crystal form but most commonly as compact mass.
The common ores and minerals containing silver are Argentite, tetrahedrite, galena, native silver, acanthite, etc. The deposits of silver are found in Mexico, China, Bolivia, Germany, Norway, and Canada.
Silver is also mined along with copper, zinc, lead, nickel, and gold.
Properties of Silver
Pure silver is white in color, soft, lustrous, ductile, and malleable. It is stable in oxygen and water but in air, it tarnishes due to the reaction of sulfur compounds which form a black layer. It mostly does not react as it is not chemically active but can be attacked by nitric and hot concentrated sulphuric acid.
It is the best conductor of electricity and has high conductivity among all metals. Silver is used as a standard to measure the conductivity of other metals. But due to its expensive cost, it is not generally used in wires.
The melting point of silver is 961.78°C and its boiling point is 2162°C. It has a density of 10.501 grams per cubic centimeter. It exists as solid at room temperature.
Silver in Biological Systems
Silver has no known significant biological role. Silver is considered to be non-toxic for humans. However, if ingested in large amounts can cause a condition called argyria turning skin color and mucous membranes greyish.
Silver compounds and their salts are poisonous and considered to have antiseptic properties. Silver can kill bacteria and other lower organisms efficiently.
Uses of Silver
- The main use of silver is as a precious metal “Sterling silver” (an alloy with 92% silver) in Jewelry, silverware, and other decorative products.
- It is used in making printed circuit boards with silver paints, high-quality electrical switches, and sometimes solders.
- It is an excellent reflector of visible light. This property makes it used in mirror coatings.
- Silver iodide is used in artificial rain cloud systems.
- Silver is used in manufacturing silver-zinc and silver-cadmium batteries.
- Silver is used as a catalyst in oxidation reactions.
- It is also used in making coins and other silver artifacts.
Isotopes of Silver
There are almost 35 known isotopes of silver whose mass number ranging from 94 to 128. Ag- 107 and Ag- 109 are two naturally occurring stable isotopes whose abundance is 51.8% and 48.2 % respectively.