Nomenclature
CAS number: 7440-22-4
Description and references
Ag; at. wt 107.8682; at. no. 47; valence 1,
2. Group IB (11). Occurrence in the earth's crust: 0.1 ppm; also
present in seawater: 0.01 ppm. Natural isotopes: 107 (51.35%);
109 (48.65%); artificial isotopes (mass numbers): 100-106, 108, 110-117.
One of the earliest known metals. Found native or associated with
copper, gold and lead. Principle ores are argentite, cerargyrite or horn silver (mixture of halides), proustite (3Ag2S.As2S3), pyrargyrite (Ag2S.Sb2S3). Extraction
from ores: Percy et al., cited by Mellor, A Comprehensive Treatise on Inorganic and Theoretical
Chemistry 3, 301 (1928); Silver, Its Economics, Extraction, Use, A. Butts, C.
D. Coxe, Eds. (Van Nostrand, Princeton, 1967) 480 pp. Reviews: Thompson, “Silver” in Comprehensive Inorganic
Chemistry vol. 3, J. C. Bailar, Jr. et
al., Eds. (Pergamon Press, Oxford, 1973) pp 79-128; G. H. Sistare
and H. B. Lockhart in Kirk-Othmer Encyclopedia
of Chemical Technology vol. 21 (Wiley-Interscience,
New York, 3rd ed., 1983) pp 1-32. Review of toxicology and human
exposure: Toxicological Profile for Silver (PB91-180430, 1990) 157 pp.
Properties
White metal, face-centered cubic structure. More
malleable and ductile than any other metal except gold; excellent
conductor of heat and electricity. mp 960.5°. bp ≈2000°. d15 10.49. Not attacked by water or atmospheric
oxygen; blackened by ozone, by hydrogen sulfide, by sulfur. Inert
to most acids; readily reacts with dil nitric acid, hot concd sulfuric
acid; superficially attacked by hydrochloric acid. Sol in fused alkali
hydroxides in presence of air, in fused alkali peroxides, in alkali
cyanides in presence of air or oxygen. Most silver salts are light-sensitive.Caution
Potential symptoms of overexposure
to dust are blue-gray eyes, nasal septum, throat and skin; irritation
and ulceration of skin; GI disturbance. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH
97-140, 1997) p 280. Blue-gray discoloration, known as argyria or
argyrosis, results from chronic exposure to silver or silver salts.
See Patty's Industrial Hygiene
and Toxicology vol. 2A, G. D. Clayton, F. E.
Clayton, Eds. (Wiley-Interscience, New York, 3rd ed., 1981) pp 1881-1894.Use
For coinage, most frequently alloyed with copper
or gold; for manuf tableware, mirrors, jewelry, ornaments; for electroplating;
for making vessels and apparatus used in manuf medicinal chemicals,
in processing foods and beverages, in handling organic acids; as catalyst
in hydrogenation and oxidation processes; as ingredient of dental
alloys. Has been used for purification of drinking water because
of toxicity to bacteria and lower forms of life. Some salts used
in photography.