Silver is general y described as a soft, white, lustrous metal ic chemical element. It occurs natural y in its pure form, as an al oy with other metal ic elements (especial y gold), and in chlorargyrite and other minerals.
As one of three coinage metals (the other two being copper and gold), silver is very mal eable and ductile.
Of the different metals, silver is known to have the highest thermal conductivity. Similarly of the different known elements, silver has the highest electrical conductivity. Provided below are some of the properties of this precious metal.
General:
• Chemical Symbol: Ag
• Atomic Number: 47
• Category (as an element): Transition Metal
• Group/ Period/ Block (in the Periodic Table): 11/ 5/ d
• Atomic Weight: 107.8682 g.mol-1
• Electron Configuration: [Kr] 4d10 5s1
Physical:
• Density (near room temperature): 10.49 g.cm-3
• Liquid Density (at melting point): 9.320 g.cm-3
• Melting Point: 961.78°C, 1234.93°F, 2041.4°K
• Boiling Point: 2162°C, 3924°F, 2435°K
• Heat of Fusion: 11.28 kJ.mol-1
• Heat of Vaporization: 250.58 kJ.mol-1
Atomic:
• Oxidation States: 1, 2, 3
• Electronegativity: 1.93 (Pauling scale)
• Atomic Radius: 144 picometre
• Covalent Radius: 145±5 picometre
• Van der Waals Radius: 172 picometre
• Ionization Energies: 731 kJ.mol-1 (first), 2070 kJ.mol-1 (second), 3361 kJ.mol-1 (third)
Despite having higher electrical conductivity than copper, silver isn't as much used for electrical purposes as copper is. There are two reasons for this: first is that silver has a greater tendency to tarnish; and second is that silver is much more expensive.
As a precious metal, silver has been much valued for ages with its so many applications, as in the following: 1. Jewelry (sterling silver is used in making fine jewelry and watches).
2. Silverware (sterling silver is also used in making utensils, tableware and ornaments).
3. Photography (silver nitrate and silver halides are used in making films).
4. Electrical and electronic products (silver paints are used in making printed circuits; silver electrical contacts are used in making computer keyboards).
5. Dentistry (silver-mercury al oy is used in making dental amalgams).
6. Optics and mirrors.
7. Various industrial and commercial uses (silver is ideal for use as a catalyst in chemical reactions).
8. Clothing (silver ions are mixed with the polymer to make yarns).
9. Medicine (silver compounds and silver ions have toxic effect on some viruses, fungi and bacteria, but not on humans).
10. Currency or coinage (as in silver bul ion).
The principal sources of silver are copper, lead, zinc and gold ores. It also occurs in the minerals chlorargyrite and argentite.
Of course, silver occurs natively, too. Some of the top silver-producing countries in the world are the United States, Canada, Peru, and Mexico. Fine silver, which has no less than 99.9% silver, is available commercial y.
Because of competing store-of-value and industrial demands, the price of silver has fluctuated considerably over the last century.
As of the beginning of 2010, the price of this precious metal is estimated at about 18 U.S. dollars per troy ounce (or 588 U.S. dollars per kilogram).
Written By Simon Newcombe
Silver As An Investment: Ways Of Investing In Silver
Silver is like three other precious metals (gold, pal adium, and platinum) in terms of being regarded as an investment commodity. In fact, this precious metal has been regarded as a form of currency and a store of value for over four centuries.
There are different ways by which one may invest in silver. Six are presented here:
Buying silver coins:
This is a popular way of taking hold of silver - physical y. Perhaps the best example of a silver coin is the Canadian Silver Maple Leaf, which consists of 99.99% pure silver. Silver coins may either be "fine silver" or
"junk silver". Junk silver coins are older coins with a lower percentage of silver. Examples of these are the dime, quarter, and fifty-cent U.S. coins minted in 1964 or earlier. These coins contain 90% silver and are 8/10 troy ounce per 1 USD of face value.
Buying silver bullion bars:
This is the most traditional way of investing in silver. Silver bul ion bars can be bought or sold over the counter in most banks in Switzerland. They may be stored in safe deposit boxes in banks or placed in non-fungible (al ocated) or pooled (unal ocated) storage with a silver dealer.
Opening a silver IRA account: Our Recommended Top silver IRA Company
An investor may open a silver account with one of the major banks in Switzerland. Here, silver can be bought or sold over the counter just like any foreign currency. However, the bank client does not own the actual silver metal. Instead, he/she has a claim against the bank for a specified quantity of the metal. A silver account is backed through either al ocated or unal ocated storage.
Owning a silver certificate:
In lieu of storing actual silver bul ion, an investor may opt for ownership of a silver certificate. A silver certificate al ows an investor to buy and sel the security sans the inconveniences associated with the physical silver's transfer. The Perth Mint Certificate Programme, which is ful y guaranteed by the
Government of Western Australia, is the only silver certificate program in the world that is guaranteed by a national government.
Trading in Exchange-Traded Funds (ETFs):
An investor can have an easy way of gaining exposure to the price of silver through an ETF. Some of the wel -known ETFs include iShares Silver Trust (with ticker symbol NYSE: SLV), Central Fund of Canada (with ticker symbols TSX: CEF.NV.A, NYSE: CEF), and ETFS Silver Trust (with ticker symbol NYSE: SIVR). Trading in ETFs means doing away with the inconveniences associated with the handling of physical silver bars.
Entering in a Contract For Difference (CFD):
Some of the noted financial services firms, especial y those in the United Kingdom, provide Contract for Difference (CFD). In this silver investment vehicle, two parties (a "buyer" and a "sel er") enter into a contract, in which the sel er agrees to pay the buyer the difference between the current value of silver and its value at contract time. In case the difference is negative, the sel er receives payment instead from the buyer. A CFD, therefore, al ows an investor to take advantage of long or short positions, enabling him/her to speculate on these markets.
It must be mentioned here though that silver has lost its forced tender status in the United States since the abandonment of the silver standard, when, on August 15, 1967, then U.S. President Lyndon B. Johnson announced that the U.S. would discontinue redeeming currency for silver (or any other precious metal).
Written By Simon Newcombe
The Eight Precious Metals Considered Noble Metals
Most metal ic chemical elements are known to easily oxidize and corrode, especial y at high temperatures.
Metals that have excel ent resistance to oxidation and corrosion, even at high temperatures, are cal ed noble metals. While there is no strict definition for this group of metals, it usual y includes those that are extremely rare.
Thus, metals that are labeled "precious" are also considered noble metals (note, however, that noble metals are not necessarily precious metals). There are nine known precious metals - gold, platinum, iridium, pal adium, osmium, silver, rhodium, ruthenium, and rhenium. With the exception of the latter, al are considered noble metals.
Using the "aqua regia" test (aqua regia is a mixture of concentrated nitric acid and concentrated hydrochloric acid, which is highly corrosive), here's how the eight precious-noble metals react:
• Gold, platinum, pal adium, and osmium dissolve.
• Ruthenium dissolves only in the presence of oxygen.
• Rhodium dissolves only when it is in a fine, pulverized form.
• Iridium and silver do not dissolve under any condition.
In another definition, noble metals may refer to electrical y conductive elements. Here, the term "noble"
serves as a modifying word, such that the electrical conductivity of materials is graded from noble to active.
Using this definition for noble metals then, we wil find that silver is less noble than, say, graphite (although graphite is an elemental form of carbon and, therefore, is not considered a metal).
Below is a comparison of the chemical nobility of the precious metals (again, excluding rhenium), with details of their specific electronic configurations, simplified reactions (as per the pH diagram), and electrode potentials. The list is presented in order of increasing atomic number.
1. Ruthenium - VIIIb/5; Ru -> Ru2+ + 2 e-; 0.455 V
2. Rhodium - VIIIb/5; Rh -> Rh2+ + 2 e-; 0.600 V
3. Pal adium - VIIIb/5; Pd -> Pd2+ + 2 e-; 0.987 V
4. Silver - Ib/5; Ag -> Ag+ + e-; 0.7996 V
5. Osmium - VIIIb/6; Os + 4 H2O -> OsO4 + 8 H+ + 8 e-; 0.838 V
6. Iridium - VIIIb/6; Ir -> Ir3+ + 3 e-; 1.156 V
7. Platinum - VIIIb/6; Pt -> Pt2+ + 2 e-; 1.18 V
8. Gold - Ib/6; Au -> Au3+ + 3 e-; 1.498 V
The second item appearing after the name of the metal (the three items are separated by semi-colons) represents the metal's reaction in water. In the pH diagram, the pH symbol is labeled on the horizontal axis to signify the -log function of the concentration of H+ ion. The lines, which represent equilibrium for the concentration, are drawn for ions at unit activity. Other concentrations may be represented by additional lines. The voltage potential is represented by a vertical axis, which is labeled Eh, where "h" stands for hydrogen.
Physics has an even more strict definition for noble metals. Here, it is required that the electronic structure's d-bands are fil ed. If this definition is followed, only gold and silver (among the precious metals) qualify as noble metals. Also note that the varying reactivity of the precious metals can readily be observed while preparing their surfaces in the vacuum regime cal ed ultra high vacuum.
Written By Simon Newcombe
The Four Platinum Bullion Coins: A Brief Description Of Each
Bul ion coins are coins made from precious metals. Their market values are determined by their inherent precious metal contents. As such bul ion coins are mainly kept as investments or stores of value.
Most of the bul ion coins available are made from silver or gold. A few also come in platinum though, including the American Platinum Eagle, the Canadian Platinum Maple Leaf, the Australian Platinum Koala, and the Manx Noble. Here's a quick run-down of each of these four platinum bul ion coins:
The American Platinum Eagle:
The American Platinum Eagle bul ion coins were first minted and released in 1997 by the United States Mint. They are offered in four varieties:
1. 1/10 ounce (oz.) coin - With a face value of USD10, 3.112 grams (g) in weight, 0.95 mil imeters (mm) thick, and 16.5 mm in diameter.
2. 1/4 oz. coin - With a face value of USD25, 7.78 g in weight, 1.32 mm thick, and 22 mm in diameter.
3. 1/2 oz. coin - With a face value of USD50, 15.56 g in weight, 1.75 mm thick, and 27 mm in diameter.
4. 1 oz. coin - With a face value of USD100, 31.12 g in weight, 2.39 mm thick, and 32.7 mm in diameter.
Al coin varieties consist of 0.9995 fine platinum. One interesting feature of the American Platinum Eagle coin is that its reverse design changes every year.
The Canadian Platinum Maple Leaf:
The Canadian Platinum Maple Leaf bul ion coins were issued from 1988 until 2002 by the Royal Canadian Mint (RCM). They were offered in four varieties: 1/10 oz. coin (with a face value (FV) of CD5), 1/4 oz. coin (FV: CD10), 1/2 oz. coin (FV: CD20), and 1 oz. coin (FV: CD50).
Two additional varieties, 1/20 oz. coin (FV: CD1) and 1/15 oz. coin (FV: CD2), were issued by RCM, but only in 1994. In 2009, the 1 oz. coin was reintroduced. Al coins, which have legal tender status in Canada, consist of 0.9995 pure platinum.
The Australian Platinum Koala:
The Australian Platinum Koala bul ion coins were first released in 1988 by the Perth Mint, the oldest currently operating mint in Australia. The coin comes in 1 oz. variety, with a face value of AD100. As with most other bul ion coins, this value is much lower than the coin's bul ion value.
On the coin's obverse is a koala, in sunken relief (i.e., lowered from the coin's plane); on the reverse is Queen Elizabeth II. The coin has legal tender status in Australia.
The Manx Noble:
The Manx Noble platinum bul ion coins were minted from 1983 to 1989 by the Pobjoy Mint, the leading private mint in Europe. The coins were offered in five varieties:
1. 1/20 oz. coin - With 1.555 g platinum content, 1.556 g in weight, and 13.9 mm in diameter.
2. 1/10 ounce coin - With 3.11 g platinum content, 3.112 g in weight, and 16.5 mm in diameter.
3. 1/4 ounce coin - With 7.776 g platinum content, 7.78 g in weight, and 22 mm in diameter.
4. 1/2 ounce coin - With 15.552 g platinum content, 15.6 g in weight, and 27 mm in diameter.
5. 1 ounce coin - With 31.103 g platinum content, 31.119 g in weight, and 32.7 mm in diameter.
The coins have no currency value. Their value, rather, is equal to their respective platinum contents. Al coins consist of 0.9995 pure platinum.
On the coin's obverse is Queen Elizabeth II, along with these texts: "ISLE OF MAN" and "ELIZABETH II". On the reverse are a Viking ship, the denomination, platinum content, and the words "Platinum fine".
Written By Simon Newcombe
The Six Precious Metals Of The Platinum Group
In the periodic table of elements, six metal ic elements are bunched together in the d-block, specifical y in groups 8 to 9, periods 5 and 6. Al transition metals, these six elements are collectively referred to as the
"platinum group metals". These precious metals tend to occur with one another in mineral deposits.
Likewise, they are alike in both chemical and physical properties.
In the order of their arrangement in the periodic table, the six metal ic elements of the platinum group are ruthenium, rhodium, pal adium, osmium, iridium, and platinum. A brief description of each of these
precious metals is provided below.
1. Ruthenium - This element is represented by the symbol Ru. Its atomic number is 44. It is mostly found in platinum ores and often used in platinum al oys as a catalyst. Its two main physical characteristics refer to its hardness as a metal and to its silvery-white colour. The former characteristic makes ruthenium ideal for use in making wear-resistance electrical contacts. The price of this precious metal as of January 2010 is estimated to be about USD173 per troy ounce (USD5,562 per kilogram).
2. Rhodium - This element is represented by the symbol Rh. Its atomic number is 45. Its occurrence is similar to that of ruthenium, and its primary use is as a catalytic converter. Rhodium is considered perhaps the rarest element. It is also known to be the most expensive precious metal, with a price estimated to be about USD2,750 per troy ounce (USD88,415 per kilogram) as of January 2010.
3. Palladium - This element is represented by the symbol Pd. Its atomic number is 46. It is also considered one of the rarest precious metals. Pal adium closely resembles its co-member in the platinum group -
platinum. It is soft and is silvery-white in colour. Like rhodium, pal adium is largely used as a catalytic converter. As of January 2010, the price of this metal is estimated to be approximately USD424 per troy ounce (USD13,632 per kilogram).
4. Osmium - This element is represented by the symbol Os. Its atomic number is 76. It is found in nature as an al oy in platinum ores. Osmium is considered the densest natural element. It is brittle and is blue-gray in colour. Because of its hardness, osmium is al oyed with the other metals in its group and used in electrical contacts and high-quality fountain pen tips. The price of osmium, as of January 2010, is about USD32.15 per troy ounce (USD12,217 per kilogram).
5. Iridium - This element is represented by the symbol Ir. Its atomic number is 77. Like osmium, iridium is very hard and brittle; it has a different color though - silvery-white. Its principal use is for electrical purposes, mainly because of its density and its high resistance to corrosion even at extremely high temperatures. Iridium is considered the fourth least abundant element in the Earth's crust, after rhenium, ruthenium, and rhodium. Its price is estimated to be about USD408 per troy ounce (USD13,117 per
kilogram) as of January 2010.
6. Platinum - This element, after which this group of precious metals is named, is represented by the symbol Pt. Its atomic number is 78. Platinum is dense, ductile, and mal eable; it is gray-white in color.
Known to be highly resistant to corrosion, this precious metal is used in jewelry, electrical contacts, and laboratory equipment. Its price, as of January 2010, is USD1,555 per troy ounce (USD49,995 per kilogram), making it the second most expensive precious metal, after rhodium.
Evident from the description of each of these six precious metals is that al of them have outstanding catalytic properties and high resistance to tarnish and wear. These characteristics make any of them wel suited for fine jewel ery. Additional y, their excel ent resistance to extremely high temperatures makes them ideal for many different industrial uses.
Written By Simon Newcombe
Three Methods Of Assay For Raw Precious Metals
Items of jewel ery or art made of precious metals are hal marked based on specific requirements either of the country of import or the place of manufacture. Such items, particularly those made of silver, gold, or platinum, are struck with an official mark (or series of marks), which guarantees fineness or purity of the metal used.
To determine the precious metal content in an item, certain non-destructive assay techniques are used. Two examples are the touchstone method (a very old assay method) and the X-ray fluorescence method (the modern, non-destructive assay method). While these assay methods are suited for finished goods (again because they are non-destructive), three other methods are more suited for raw precious metals:
Titration:
This assay method is one of the most widely used laboratory technique, which involves the analysis and determination of unknown concentration of a given reactant. It is used to assay silver bul ion or stock. In this method, a reagent (titrant) of a known volume and concentration is utilized to react with a solution of the substance being analyzed (titrand), whose concentration is unknown.
With the use of an instrument cal ed burette (to add the titrant), the exact consumed amount, on reaching the endpoint, can be determined. The endpoint refers to the point at which the assay is complete. The completion is signaled by an indicator. There are at least four types of titration. These are acid-base, redox, complexometric, and Zeta potential.
Cupellation:
This technique is considered the most exact, elaborate, and destructive method of assay and is best suited for gold bul ion or stock. Also cal ed fire assay, the method involves treating ores or al oyed metals under high temperatures and careful y controlled operations to separate gold from base metals (copper, zinc, or lead), which may be present in the ore. Once the base metals are heated at high temperatures, the gold (as wel as the other precious metals that may be present) remains apart and the other non-precious metals react forming other compounds. Cupel ation basical y has two processes: large scale and smal scale.
Spectrometry:
This method is best used to assay platinum bul ion or stock. With the use of a spectrometer or
spectrograph, the amount or concentration of a given substance is assessed. The substances are identified through the spectrum they absorb or emit. This assay method has several types. These include absorption, fluorescence, X-ray, flame, visible, ultraviolet, infrared, photoemission, Mossbauer, nuclear magnetic resonance, and Raman.
Again, the X-ray fluorescence (XRF) method is the modern assay method widely used today for analyzing precious metals, including (besides silver, gold, and platinum) rhenium, ruthenium, iridium, and pal adium.
As a non-destructive assay method, XRF can identify various elements in a substance (in fact, even in powder and liquid ones) within a few minutes.
One of the most important aspects in any of the assay methods pertains to the accurate determination of the composition of a substance at various points in the process. Controlling and minimizing metal losses can only be achieved through close monitoring of the composition of the work in progress.