Silver

Silver - Ag

CAS: 7440-22-4
Description: Soft, silver metal
Classification: Transition Metal
Date of Discovery: Known to the ancients
Discoverer: Unknown
Name Origin: Old English seolfor, "silver"
Symbol Origin: Latin argentum, "silver"

Atomic Number: 47
Number of Neutrons: 61
Atomic Mass: 107.8682(2) amu
Melting Point: 961.78 °C
Boiling Point: 2162 °C
Density (293 K): 10.50 g/cm³
Atomic volume: 10.3 cm³/mol
Electrical resistivity: 0.630 10^-6/cm

Thermal conductivity: 4.29 W/cmK
Enthalpy of atomization: 284.5 kJ/mol
Enthalpy of vaporization: 250.580 kJ/mol
Enthalpy of fusion: 11.30 kJ/mol
Specific heat capacity: 0.235 J/gK

Energy levels: 2-8-18-18-1
Electron configuration: [Kr]4d¹⁰5s¹
Crystal Structure: Cubic face centered
Atomic radius: 1.75 Å
Covalent radius: 1.34 Å
Oxidation States: +1
Electronegativity, Pauling: 1.93
Electron affinity: 1.302 eV
First ionization energy: 7.576 eV
2nd ionization energy: 21.49 eV
3rd ionization energy: 34.83 eV
Polarizability: 7.2 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
⁹⁴Ag	0.42 s	⁺, p
⁹⁵Ag	2.0 s	⁺, p
⁹⁶Ag	95.9307	5.1 s	⁺; EC
⁹⁷Ag	96.9240	19 s	⁺; EC
⁹⁸Ag	97.9218	47 s	⁺; EC	5+
^99mAg	11 s	IT	1/2-
⁹⁹Ag	98.9176	2.07 m	⁺	9/2+
^100mAg	2.3 m	⁺; EC	2+
¹⁰⁰Ag	99.9161	2.0 m	⁺; EC	5+
^101mAg	3.1 s	IT	1/2-
¹⁰¹Ag	100.9128	11.1 m	⁺; EC	9/2+
^102mAg	7.8 m	⁺; EC; IT	2+
¹⁰²Ag	101.91197	13.0 m	⁺; EC	5+
^103mAg	5.7 s	IT	1/2-
¹⁰³Ag	102.90897	1.10 h	⁺; EC	7/2+
^104mAg	33 m	⁺; EC; IT	2+
¹⁰⁴Ag	103.90863	69 m	⁺; EC	5+
^105mAg	7.2 m	IT; EC	7/2+
¹⁰⁵Ag	104.90653	41.3 d	EC	1/2-
^106mAg	8.4 d	EC	6+
¹⁰⁶Ag	105.90667	24.0 m	⁺; EC	1+
^107mAg	44.2 s	IT	7/2+
¹⁰⁷Ag	51.839(7)	106.905093	Stable	1/2-
^108mAg	130 y	EC; IT	6+
¹⁰⁸Ag	107.905954	2.39 m	^-; EC; ⁺	1+
^109mAg	39.8 s	IT	7/2+
¹⁰⁹Ag	48.161(7)	108.904756	Stable	1/2-
^110mAg	249.8 d	^-; IT	6+
¹¹⁰Ag	109.906111	24.6 s	^-	1+
^111mAg	1.08 m	IT; ^-	7/2+
¹¹¹Ag	110.905295	7.47 d	^-	1/2-
¹¹²Ag	111.90701	3.13 h	^-	2-
^113mAg	1.14 m	IT; ^-	7/2+
¹¹³Ag	112.90657	5.3 h	^-	1/2-
¹¹⁴Ag	113.90881	4.6 s	^-	1+
^115mAg	18.7 s	^-	7/2+
¹¹⁵Ag	114.90876	20 m	^-	1/2-
^116mAg	IT; ^-	5+
¹¹⁶Ag	115.91137	2.68 m	^-	2-
^117mAg	5.3 s	^-	7/2+
¹¹⁷Ag	116.91171	1.22 m	^-	1/2-
^118mAg	2.8 s	^-; IT
¹¹⁸Ag	117.9145	4.0 s	^-
¹¹⁹Ag	118.9157	2.1 s	^-	7/2+
^120mAg	0.32 s	^-; IT
¹²⁰Ag	119.9187	1.23 s	^-
¹²¹Ag	120.9200	0.78 s	^-
^122mAg	1 s	^-
¹²²Ag	121.9233	0.44 s	^-
¹²³Ag	122.9249	0.31 s	^-
¹²⁴Ag	123.9285	0.22 s	^-
Silver has been known since ancient times. It is mentioned in Genesis. Slag dumps in Asia Minor and on islands in the Aegean Sea indicate that man learned to separate silver from lead as early as 3000 B.C. Silver occurs native and in ores such as argentite (Ag₂S), light ruby silver (Ag₃ AsS₃), dark ruby silver (Ag₃SbS₃) and horn silver (AgCl); lead, lead-zinc, copper, gold, and copper-nickel ores are principal sources. Mexico, Canada, Peru, and the U.S. are the principal silver producers in the western hemisphere. Silver is also recovered during electrolytic refining of copper. Commercial fine silver contains at least 99.9% silver. Purities of 99.999+% are available commercially. Pure silver has a brilliant white metallic luster. It is a little harder than gold and is very ductile and malleable, being exceeded only by gold and perhaps palladium. Pure silver has the highest electrical and thermal conductivity of all metals, and possesses the lowest contact resistance. It is stable in pure air and water, but tarnishes when exposed to ozone, hydrogen sulfide, or air containing sulfur. The alloys of silver are important. Sterling silver is used for jewelry, silverware, etc. where appearance is paramount. This alloy contains 92.5% silver, the remainder being copper or some other metal. Silver is of utmost importance in photography, about 30% of the U.S. industrial consumption going into this application. It is used for dental alloys. Silver is used in making solder and brazing alloys, electrical contacts, and high capacity silver-zinc and silver-cadmium batteries. Silver paints are used for making printed circuits. It is used in mirror production and may be deposited on glass or metals by chemical deposition, electrodeposition, or by evaporation. When freshly deposited, it is the best reflector of visible light known, but is rapidly tarnishes and loses much of its reflectance. It is a poor reflector of ultraviolet. Silver fulminate (Ag₂C₂N₂0₂), a powerful explosive, is sometimes formed during the silvering process. Silver iodide is used in seeding clouds to produce rain. Silver chloride has interesting optical properties as it can be made transparent; it also is a cement for glass. Silvet nitrate, or lunar caustic, the most important silver compound, is used extensively in photography. While silver itself is not considered to be toxic, most of its salts are poisonous. Natural silver contains two stable isotopes. Forty nine other radioactive isotopes and isomers are known. Silver compounds can be absorbed in the circulatory system and reduced silver deposited in the various tissues of the body. A condition, known as argyria, results, with a greyish pigmentation of the skin and mucous membranes. Silver has germicidal effects and kills many lower organisms effectively without harm to higher animals. Silver for centuries has been used traditionally for coinage by many countries of the world. In recent times, however, consumption of silver has at times greatly exceeded the output. In 1939, the price of silver was fixed by the U.S. Treasury at 71 cents/troy oz., and at 90.5 cents/troy oz. in 1946. In November 1961 the U.S. Treasury suspended sales of nonmonetized silver, and the price stabilized for a time at about $1.29, the melt-down value of silver U.S. coins. The Coinage Act of 1965 authorized a change in the metallic composition of the three U.S. subsidiary denominations to clad or composite type coins. This was the first change in U.S. coinage since the monetary system was established in 1792. Clad dimes and quarters are made of an outer layer of 75% Cu and 25% Ni bonded to a central core of pure Cu. The composition of the one- and five-cent pieces remains unchanged. One-cent coins are 95% Cu and 5% Zn. Five-cent coins are 75% Cu and 25% Ni. Old silver dollars are 90% Ag and 10% Cu. Earlier subsidiary coins of 90% Ag and 10% Cu officially were to circulate alongside the clad coins; however, in practice they have largely disappeared (Gresham's Law), as the value of the silver is now greater than their exchange value. Silver coins of other countries have largely been replaced with coins made of other metals. On June 24, 1968, the U.S. Government ceased to redeem U.S. Silver Certificates with silver. Since that time, the price of silver has fluctuated widely. LINKS: Chemistry of Black and White Photography Cloud seeding Colloidal Silver Discovery Center Natural Germicide -- Silver OSHA Chemical Sampling Information Pan American Silver Corp. Silver and its compounds Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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