Silver
Silver (symbol Ag) is a chemical element. In chemistry, silver is element 47, a transition metal. It has an atomic weight of 107.86 a.m.u. Its symbol is Ag, from the Latin word for silver, argentum.
Properties
Physical properties
Silver is a soft metal. It is also a precious metal. When it is used in money or in jewellery, it is often alloyed with gold or some other metal to make it harder. It is bluish-white. Among metals, it is the most reflective and the best conductor of electricity and heat. It is considered a precious metal. It is very malleable and ductile, which means it can be pulled into wire or hammered into thin sheets. Silver is one of the few words in the English language that does not rhyme with any other word. Silver coins and bars can be bought and sold at coin shops around the world.
Chemical properties
Silver is less reactive than most other metals. It does not dissolve in most acids. Nitric acid dissolves it, though, to make silver nitrate. It does react with strong oxidizing agents like potassium dichromate or potassium permanganate. It does not corrode easily. It only corrodes when there is hydrogen sulfide in the air. Then, it forms a black coating known as tarnish.
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Silver exists in two main oxidation states: +1 and +2. The +1 is much more common. A few compounds exist in the +2 oxidation state, but they are very strong oxidizing agents. Silver compounds can be brown, black, yellow, gray, or colorless. Silver compounds are disinfectants.
- Silver(I) compounds
Silver(I) compounds are oxidizing agents. They are more common. Most of them are very expensive.
- Silver bromide, light yellow
- Silver carbonate, yellowish
- Silver chloride, white
- Silver(I) fluoride, yellow-brown
- Silver iodate, colorless
- Silver iodide, yellow
- Silver nitrate, colorless
- Silver oxide, brown-black
- Silver sulfide, black
- Silver(II) compounds
Silver(II) compounds are powerful oxidizing agents and rare.
- Silver(II) fluoride, strong oxidizing agent, highly reactive, white or gray
Occurrence
Silver can be found as a native metal. Most silver is found with copper, lead, or gold in rocks. The rocks are found mostly in Canada, Mexico, Peru, and the United States. Peru produces the most silver, mostly in mines that are operated for copper and zinc. Silver is also in chemical compounds.
Preparation
Silver is extracted from the earth in several ways. It is normally extracted using electrolysis.
Uses
As an element
Silver has been used for many thousands of years by people all over the world, for jewellery, as money, and many other things. It is called a white metal even though it looks grey. The word silver is also used to talk about this color or shade of grey. Silver is also used for utensils. It may be used to fill teeth in dentistry as an amalgam. Silver is used as a catalyst.
In compounds
Silver compounds are disinfectants. It can kill bacteria and has other useful properties. It is used in the silver oxide battery. They are also used in photographic film. They can also be used to reduce odors in clothes. Some silver compounds are used in creams that help burns heal.
History
Silver has used for thousands of years. It was normally considered second to gold in value. Many people including Romans and Chinese used silver as money. The symbol Ag is from the Latin name for silver, argentum. Silver was also used to prevent infections and decay.
Safety
Silver is not a large danger to humans. Silver compounds are toxic. They make the skin turn blue. Some can be carcinogens. Colloidal silver, a common homeopathic remedy, is not toxic in normal amounts, but it does not do much. Silver is very toxic to fish, so silver-containing waste (for example, photographic chemicals or silver oxide batteries) must not be released into the environment and should be properly recycled. Silver should not be stored near ammonia, acetylene, or strong acids, as these can react with silver to make unstable silver salts.
Market
More silver has been used each year than the amount mined in each year since 1990, when the amount mined each year stopped growing and its use increased. Companies that use silver have benefited from speculators who sell promises to deliver silver that does not exist, keeping prices artificially low. This is called naked short selling. The amount owed is more than all the silver in the world. The price of silver could go very high when the stored silver runs out and investors start asking for their metal back, instead of taking more I.O.U.'s.
The price of silver increased to 28 US dollars per troy ounce as of December 2010.
SilverChemical Properties Media
Silver is extremely ductile, and can be drawn into a wire one atom wide.
Sulfid stříbrný - Ag2S
Silver crystals forming on a copper surface in a silver nitrate solution. Video by Maxim Bilovitskiy.
Crystals of silver nitrate
Structure of the diamminesilver(I) complex, [Ag(NH3)2]+
Silver-NHCs as carbene transfer reagents. Example from Wang, Harrison M. J.; Lin, Ivan J. B. (1998). "Facile Synthesis of Silver(I)−Carbene Complexes. Useful Carbene Transfer Agents". Organometallics 17: 972. DOI:10.1021/om9709704.
Different colors of silver–copper–gold alloys
Silver vase, c. 2400 BC
Karashamb silver goblet, 23rd–22nd century BC
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Other websites
- Silver -Citizendium