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| General |
| Name, Symbol, Number | Silver, Ag, 47 |
| Chemical series | Transition metals |
| Group, Period, Block | 11, 5 , d |
| Density, Hardness | 10490 kg/m3, 2.5 |
| Appearance | Silvery |
| Atomic Properties |
| Atomic weight | 107.8682 amu |
| Atomic radius (calc.) | 160 (165) pm |
| Covalent radius | 153 pm |
| van der Waals radius | 172 pm |
| Electron configuration | [Kr]4d10 5s1 |
| e- 's per energy level | 2, 8, 18, 18, 1 |
| Oxidation state (Oxide) | 1 (amphoteric) |
| Crystal structure | Face centered cubic |
| Physical Properties |
| State of matter | Solid (--) |
| Melting point | 1234.93 K (1763.2 °F) |
| Boiling point | 2435 K (3924 °F) |
| Molar volume | 10.27 ×10-3 m3/mol |
| Heat of vaporization | 250
.58 kJ/mol |
| Heat of fusion | 11.3 kJ/mol |
| Vapor pressure | 0.34 Pa at 1234 K |
| Speed of sound | 2600 m/s at 293.15 K |
| Miscellaneous |
| Electronegativity | 1.93 (Pauling scale) |
| Specific heat capacity | 232 J/(kg*K) |
| Electrical conductivity | 63 106/m ohm |
| Thermal conductivity | 429 W/(m*K) |
| 1st ionization potential | 731.0 kJ/mol |
| 2nd ionization potential | 2070 kJ/mol |
| 3rd ionization potential | 3361 kJ/mol |
| Most Stable Isotopes |
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| SI units & STP are used except where noted. |
Silver is a
chemical element in the
periodic table that has the symbol Ag and
atomic number 47. A soft white lustrous
transition metal, silver has the highest electrical and thermal conductivity of any metal and occurs in
minerals and in free form. This metal is used in
coins,
jewelry, tableware and
photography.
Silver is a very ductile and malleable (slightly harder than
gold) univalent
coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest
electrical conductivity of all metals, even higher than
copper, but its greater cost has prevented it from being widely used in place of copper for electrical purposes.
Pure silver also has the highest thermal conductivity, whitest color, the highest optical reflectivity (although it is a poor reflector of ultraviolet), and the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for the effect of light upon them. This metal is stable in pure air and water, but does tarnish when it is exposed to ozone, hydrogen sulfide, or air with sulfur in it. The most common oxidation states of silver are +1 and +2.
The principal use of silver is as a precious metal and its
halide salts, especially
silver nitrate, are also widely used in
photography (which is the largest single end use of silver). Other uses;
- Silver has many industrial applications such as in mirrors, electrical and electronic products.
- Silver's catalytic properties make it ideal for use as a catalyst in oxidation reactions; for example, the production of formaldehyde from methanol and air by means of silver screens or crystallites[?] containing a minimum 99.95 weight-percent silver.
- Sterling silver alloy (92.5% silver) is used for jewelry, silverware[?] and other places where appearance is important.
- This metal is used in dental alloys that make fittings and fillings.
- Used to make solder and brazing alloys, electrical contacts[?], and high capacity silver-zinc and silver-cadmium batteries.
- Printed circuits are made using silver paints.
- Silver fulminate[?] is a powerful explosive.
- Silver chloride[?] can be made transparent and is used as a cement for glass.
- Since 400 B.C. silver has been employed by many countries to make coins used in monetary exchange. In many languages the words for "silver" and "money" are the same.
- Silver iodide[?] has been used in attempts to seed clouds to produce rain.
Silver (
Anglo-Saxon,
Seolfor siolfur; Ag is from the
Latin argentum) has been known since ancient times. It is mentioned in the
book of Genesis and slag heaps found in
Asia Minor and on the islands of the
Aegean Sea indicate that silver was being separated from
lead as early as the
4th millennium BC.
Silver has been used for thousands of years as ornaments and utensils[?], for trade, and as the basis for many monetary systems[?]. It was long considered the second most precious metal, second only to gold, and was known under the name of luna to the ancients and alchemists. The alchemical symbol for silver is a half-moon with the open part on the left.
Europeans, found huge amount of silver in the New World, in Zacatecas, Mexico and Potosí, which triggered a period of inflation in Europe.
Argentina was named after the metal. Plata, as in Rio de la Plata is the Spanish word for silver
Silver is found in native form, combined with
sulfur,
arsenic,
antimony, or
chlorine and in various ores such as
argentite[?] (Ag
2S) and
horn silver[?] (Ag
Cl). The principal sources of silver are
copper, copper-
nickel,
gold,
lead and lead-
zinc ores obtained from
Canada,
Mexico,
Peru, and the
United States.
This metal is also produced during the electrolytic refining of copper. Commercial grade fine silver is at least 99.9% pure silver and purities greater than 99.999% are available.
Naturally occurring silver is composed of the two stable
isotopes Ag-107 and Ag-109 with Ag-107 being the most abundant (51.839%
natural abundance). Twenty-eight
radioisotopes have been characterized with the most stable being Ag-105 with a
half-life of 41.29 days, Ag-111 with a half-life of 7.45 days, and Ag-112 with a half-life of 3.13 hours. All of the remaining
radioactive isotopes have half-lifes that are less than an hour and the majority of these have half lifes that are less than 3 minutes. This element also has numerous
meta states with the most stable being Agm-128 (t
˝ 418 years), Agm-110 (t
˝ 249.79 days) and Agm-107 (t
˝ 8.28 days).
Isotopes of silver range in atomic weight from 93.943 amu (Ag-94) to 123.929 amu (Ag-124). The primary decay mode before the most abundant stable isotope, Ag-107, is electron capture and the primary mode after is beta decay. The primary decay products before Ag-107 are palladium (element 46) isotopes and the primary products after are cadmium (element 48) isotopes.
The palladium isotope Pd-107 decays by beta emission to Ag-107 with a half-life of 6.5 million years. Iron meteorites are the only objects with a high enough Pd/Ag ratio to yield measurable variations in Ag-107 abundance. Radiogenic Ag-107 was first discovered in the Santa Clara meteorite in 1978. The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. Pd-107 versus Ag correlations observed in bodies, which have clearly been melted since the accretion of the solar system, must reflect the presence of live short-lived nuclides in the early solar system.
Silver itself is not toxic but most of its salts are poisonous and may be carcinogenic. Compounds containing silver can be absorbed into the
circulatory system and become deposited in various body tissues leading to the condition called
argyria which results in a grayish skin pigmentation and mucus membranes. Silver has germicidal effects and kills many microbial organisms without causing noticeable harm to more complex life-forms. This metal plays no natural biological role in humans.
Mexico is the largest silver producer. According to the Secretary of Economics of Mexico, it has produced in 2000, 2747 tons, about 15% of the annual production of the world.
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