Atomic Number: 47
Atomic Weight: 107.8682
Discovery: Known since prehistoric time. Man learned to separate silver from lead as early as 3000 B.C.
Electron Configuration: [Kr]5s14d10
Word Origin: Anglo-Saxon Seolfor or siolfur; meaning 'silver', and Latin argentum meaning 'silver'
Properties: The melting point of silver is 961.93°C, boiling point is 2212°C, specific gravity is 10.50 (20°C), with a valence of 1 or 2. Pure silver has a brilliant white metallic luster. Silver is slightly harder than gold. It is very ductile and malleable, exceeded in these properties by gold and palladium. Pure silver has the highest electrical and thermal conductivity of all metals. Silver possesses the lowest contact resistance of all metals. Silver is stable in pure air and water, although it tarnishes upon exposure to ozone, hydrogen sulfide, or air containing sulfur.
Uses: The alloys of silver have many commercial uses. Sterling silver (92.5% silver, with copper or other metals) is used for silverware and jewelry. Silver is used in photography, dental compounds, solder, brazing, electrical contacts, batteries, mirrors, and printed circuits. Freshly deposited silver is is the best known reflector of visible light, but it rapidly tarnishes and loses its reflectance. Silver fulminate (Ag2C2N2O2) is a powerful explosive. Silver iodide is used in cloud seeding to produce rain. Silver chloride can be made transparent and is also used as a cement for glass. Silver nitrate, or lunar caustic, is used extensively in photography. Although silver itself is not considered toxic, most of its salts are poisonous, due to the anions involved. Exposure to silver (metal and soluble compounds) should not exceed 0.01 mg/M3 (8 hour time-weighted average for a 40 hour week). Silver compounds can be absorbed into the circulatory system, with deposition of reduced silver in body tissues. This may result in argyria, which is characterized by a greyish pigmentation of the skin and mucous membranes. Silver is germicidal and may be used to kill many lower organisms without harm to higher organisms. Silver is used as coinage in many countries.
Sources: Silver occurs native and in ores incuding argentite (Ag2S) and horn silver (AgCl). Lead, lead-zinc, copper, copper-nickel, and gold ores are other prinicipal sources of silver. Commercial fine silver is at least 99.9% pure. Commercial purities of 99.999+% are available.
Element Classification: Transition Metal
Density (g/cc): 10.5
Appearance: silvery, ductile, malleable metal
Isotopes: There are 38 known isotopes of silver ranging from Ag-93 to Ag-130. Silver has two stable isotopes: Ag-107 (51.84% abundance) and Ag-109 (48.16% abundance).
Atomic Radius (pm): 144
Atomic Volume (cc/mol): 10.3
Covalent Radius (pm): 134
Ionic Radius: 89 (+2e) 126 (+1e)
Specific Heat (@20°C J/g mol): 0.237
Fusion Heat (kJ/mol): 11.95
Evaporation Heat (kJ/mol): 254.1
Debye Temperature (K): 215.00
Pauling Negativity Number: 1.93
First Ionizing Energy (kJ/mol): 730.5
Thermal Conductivity: 429 W/m·K @ 300 K
Oxidation States: +1 (most common), +2 (less common), +3 (less common)
Lattice Structure: Face-Centered Cubic
Lattice Constant (Å): 4.090
CAS Registry Number: 7440-22-4
- Silver's element symbol Ag, is from the Latin word argentum meaning silver.
- In many cultures, and some alchemical texts, silver was associated with the Moon while gold was associated with the Sun.
- Silver has the highest electrical conductivity of all metals.
- Silver has the highest thermal conductivity of all metals.
- Silver halide crystals darken when exposed to light. This process was vital to photography.
- Silver is considered one of the noble metals.
- Silver is slightly harder (less malleable) than gold.
- Silver ions and silver compounds are toxic to many types of bacteria, algae and fungi. Silver coins used to be stored in containers of water and wine to prevent spoiling.
- Silver nitrate has been used to prevent infection in burns and other wounds.
References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952)
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