What is Silver? | Element data, Properties and Uses

What is Silver?

Silver is a white lustrous metal and the symbol of silver is Ag derived from the Latin word Argentum. The atomic number of silver is 47 and its atomic weight is 107.86. Silver is located in the d-block element, in group 11, and in the 5th period of the periodic table. Its electronic configuration is [Kr] 4d10 5s1. Silver has two stable isotopes 107Ag and 109Ag. Oxidation states range from +1 to +3, among which Ag (+1) is the most common oxidation state.

Occurrence

Silver is usually found in large quantities in Mexico and Norway, along with Cu and Au. The principal ores of Ag are,

• Sulfide ores: Argentite or silver glance, silver copper glance, and ruby silver.

• Halide ores:  Horn silver and bromyrite

Most of the copper and lead ores contain silver in small quantities. It's one of the sources of silver. Major silver-producing countries are the USA, Mexico, Peru, Canada, Bolivia, New South Wales, Barma, and Japan. There are no silver ores in India. They are obtained as the by-product in the mining of Gold and Lead.

Extraction

Extraction of silver from Argentite (Ag2S)  and horn silver (AgCl) is by Mac- Arthur and Forest process. The silver obtained by this process has impurities that are purified by the electrolytic method. The cathode is a pure silver plate, and the anode is a block of impure silver. A solution of 6% AgNO3 with 1%HNO3 is used as an electrolyte. On passing current pure silver gets deposited on the cathode.

Getting silver from argentiferous Lead is by Parke’s process, called desilverization of lead. Lead is extracted from galena ore containing the impurities of copper, silver, bismuth, arsenic, iron, zinc, tin, etc. This argentiferous lead has silver up to 2%, in this process, the ore is mixed with zinc and the mixture is melted in iron pots, silver forms zinc-silver alloy while lead is obtained in the molten state. Zinc-silver alloy on cooling gets solidified while lead is in a molten state. Zn-Ag alloy is strongly heated to distill zinc as vapors and silver is obtained in the free state. Silver obtained has some impurities of lead which can be removed by the cupellation process.

Getting silver from silver coins or ornaments; They are alloys of silver and copper. The alloy is dissolved in HNO3, and a solution containing a mixture of AgNO3 and Cu(NO3)2 is obtained. Excess nitric acid is boiled off and it is then treated with hydrochloric acid when a precipitate of silver chloride is obtained. This is converted into silver by any of the 3 methods.

• Reduction with nascent hydrogen.

• Fusion with sodium carbonate.

• Boiling with caustic soda and glucose. 

The silver obtained is further purified by fusion with borax and nitre followed by electrolytic purification

Properties

Silver is a white lustrous metal. The boiling point of silver is 2162 °C and the melting point is  961.7 °C and the specific gravity is 10.5. It is a good conductor of heat and electricity. Silver tarnishes slowly in the air as sulfur compounds react with the silver surface forming silver sulfide.

Uses

• Sterling silver contains 92.5% of silver and the rest is copper. It's used in making jewelry, ornamental vessels, coins, temples, and idols.

• Silver amalgams are used in the silvering of mirrors.

• Salts of silver like silver bromide and iodide are used in photography and light-sensitive glass.

• Silver has antibacterial properties and silver sols are used for their antibacterial effects.

• Nanoparticles: Silver nanoparticles are used in clothing to prevent bacterial growth.

• Silver is used in dentistry, for making caps, and silver complex is used to treat cavities.

• Electronics: It is used as an electrode, as it has high electrical conductivity. Printed circuits are painted with silver paints.

• Catalysts: Silver is used as a catalyst in many oxidation reactions.

• Silver foil is used in the decoration of many traditional Indian dishes.