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Silver

Silver is a chemical element with the symbol Ag (from the Latin argentum, derived from the Proto-Indo-European h₂erǵ: "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal.[5] The metal is found in the Earth's crust in the pure, free elemental form ("native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining.

Silver, 47Ag
Silver
Appearancelustrous white metal
Standard atomic weight Ar°(Ag)
  • 107.8682±0.0002
  • 107.87±0.01 (abridged)[1]
Silver in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Cu

Ag

Au
palladiumsilvercadmium
Atomic number (Z)47
Groupgroup 11
Periodperiod 5
Block  d-block
Electron configuration[Kr] 4d10 5s1
Electrons per shell2, 8, 18, 18, 1
Physical properties
Phase at STPsolid
Melting point1234.93 K ​(961.78 °C, ​1763.2 °F)
Boiling point2435 K ​(2162 °C, ​3924 °F)
Density (near r.t.)10.49 g/cm3
when liquid (at m.p.)9.320 g/cm3
Heat of fusion11.28 kJ/mol
Heat of vaporisation254 kJ/mol
Molar heat capacity25.350 J/(mol·K)
Vapour pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1283 1413 1575 1782 2055 2433
Atomic properties
Oxidation states−2, −1, 0,[2] +1, +2, +3 (an amphoteric oxide)
ElectronegativityPauling scale: 1.93
Ionisation energies
  • 1st: 731.0 kJ/mol
  • 2nd: 2070 kJ/mol
  • 3rd: 3361 kJ/mol
Atomic radiusempirical: 144 pm
Covalent radius145±5 pm
Van der Waals radius172 pm
Spectral lines of silver
Other properties
Natural occurrenceprimordial
Crystal structureface-centred cubic (fcc)
Speed of sound thin rod2680 m/s (at r.t.)
Thermal expansion18.9 µm/(m⋅K) (at 25 °C)
Thermal conductivity429 W/(m⋅K)
Thermal diffusivity174 mm2/s (at 300 K)
Electrical resistivity15.87 nΩ⋅m (at 20 °C)
Magnetic orderingdiamagnetic[3]
Molar magnetic susceptibility−19.5×10−6 cm3/mol (296 K)[4]
Young's modulus83 GPa
Shear modulus30 GPa
Bulk modulus100 GPa
Poisson ratio0.37
Mohs hardness2.5
Vickers hardness251 MPa
Brinell hardness206–250 MPa
CAS Number7440-22-4
History
Discoverybefore 5000 BC
Symbol"Ag": from Latin argentum
Isotopes of silver
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
105Ag syn 41.3 d ε 105Pd
γ
106mAg syn 8.28 d ε 106Pd
γ
107Ag 51.839% stable
108mAg syn 439 y ε 108Pd
IT 108Ag
γ
109Ag 48.161% stable
110m2Ag syn 249.86 d β 110Cd
γ
111Ag syn 7.43 d β 111Cd
γ
 Category: Silver
| references

Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes alongside gold:[6] while it is more abundant than gold, it is much less abundant as a native metal.[7] Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of the seven metals of antiquity, silver has had an enduring role in most human cultures.

Other than in currency and as an investment medium (coins and bullion), silver is used in solar panels, water filtration, jewellery, ornaments, high-value tableware and utensils (hence the term "silverware"), in electrical contacts and conductors, in specialized mirrors, window coatings, in catalysis of chemical reactions, as a colorant in stained glass, and in specialized confectionery. Its compounds are used in photographic and X-ray film. Dilute solutions of silver nitrate and other silver compounds are used as disinfectants and microbiocides (oligodynamic effect), added to bandages, wound-dressings, catheters, and other medical instruments.

Characteristics

 
Silver is extremely ductile, and can be drawn into a wire one atom wide.[8]

Silver is similar in its physical and chemical properties to its two vertical neighbours in group 11 of the periodic table: copper, and gold. Its 47 electrons are arranged in the configuration [Kr]4d105s1, similarly to copper ([Ar]3d104s1) and gold ([Xe]4f145d106s1); group 11 is one of the few groups in the d-block which has a completely consistent set of electron configurations.[9] This distinctive electron configuration, with a single electron in the highest occupied s subshell over a filled d subshell, accounts for many of the singular properties of metallic silver.[10]

Silver is a relatively soft and extremely ductile and malleable transition metal, though it is slightly less malleable than gold. Silver crystallizes in a face-centered cubic lattice with bulk coordination number 12, where only the single 5s electron is delocalized, similarly to copper and gold.[11] Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of silver.[12]

Silver has a brilliant, white, metallic luster that can take a high polish,[13] and which is so characteristic that the name of the metal itself has become a colour name.[10] Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm.[14] At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm.[15]

Very high electrical and thermal conductivity are common to the elements in group 11, because their single s electron is free and does not interact with the filled d subshell, as such interactions (which occur in the preceding transition metals) lower electron mobility.[16] The thermal conductivity of silver is among the highest of all materials, although the thermal conductivity of carbon (in the diamond allotrope) and superfluid helium-4 are higher.[9] The electrical conductivity of silver is the highest of all metals, greater even than copper. Silver also has the lowest contact resistance of any metal.[9] Silver is rarely used for its electrical conductivity, due to its high cost, although an exception is in radio-frequency engineering, particularly at VHF and higher frequencies where silver plating improves electrical conductivity because those currents tend to flow on the surface of conductors rather than through the interior. During World War II in the US, 13540 tons of silver were used for the electromagnets in calutrons for enriching uranium, mainly because of the wartime shortage of copper.[17][18][19]

Silver readily forms alloys with copper, gold, and zinc. Zinc-silver alloys with low zinc concentration may be considered as face-centred cubic solid solutions of zinc in silver, as the structure of the silver is largely unchanged while the electron concentration rises as more zinc is added. Increasing the electron concentration further leads to body-centred cubic (electron concentration 1.5), complex cubic (1.615), and hexagonal close-packed phases (1.75).[11]

Isotopes

Naturally occurring silver is composed of two stable isotopes, 107Ag and 109Ag, with 107Ag being slightly more abundant (51.839% natural abundance). This almost equal abundance is rare in the periodic table. The atomic weight is 107.8682(2) u;[20][21] this value is very important because of the importance of silver compounds, particularly halides, in gravimetric analysis.[20] Both isotopes of silver are produced in stars via the s-process (slow neutron capture), as well as in supernovas via the r-process (rapid neutron capture).[22]

Twenty-eight radioisotopes have been characterized, the most stable being 105Ag with a half-life of 41.29 days, 111Ag with a half-life of 7.45 days, and 112Ag with a half-life of 3.13 hours. Silver has numerous nuclear isomers, the most stable being 108mAg (t1/2 = 418 years), 110mAg (t1/2 = 249.79 days) and 106mAg (t1/2 = 8.28 days). All of the remaining radioactive isotopes have half-lives of less than an hour, and the majority of these have half-lives of less than three minutes.[23]

Isotopes of silver range in relative atomic mass from 92.950 u (93Ag) to 129.950 u (130Ag);[24] the primary decay mode before the most abundant stable isotope, 107Ag, is electron capture and the primary mode after is beta decay. The primary decay products before 107Ag are palladium (element 46) isotopes, and the primary products after are cadmium (element 48) isotopes.[23]

The palladium isotope 107Pd decays by beta emission to 107Ag with a half-life of 6.5 million years. Iron meteorites are the only objects with a high-enough palladium-to-silver ratio to yield measurable variations in 107Ag abundance. Radiogenic 107Ag was first discovered in the Santa Clara meteorite in 1978.[25] 107Pd–107Ag correlations observed in bodies that have clearly been melted since the accretion of the Solar System must reflect the presence of unstable nuclides in the early Solar System.[26]

Chemistry

Oxidation states and stereochemistries of silver[27]
Oxidation
state
Coordination
number
Stereochemistry Representative
compound
0 (d10s1) 3 Planar Ag(CO)3
1 (d10) 2 Linear [Ag(CN)2]
3 Trigonal planar AgI(PEt2Ar)2
4 Tetrahedral [Ag(diars)2]+
6 Octahedral AgF, AgCl, AgBr
2 (d9) 4 Square planar [Ag(py)4]2+
3 (d8) 4 Square planar [AgF4]
6 Octahedral [AgF6]3−

Silver is a rather unreactive metal. This is because its filled 4d shell is not very effective in shielding the electrostatic forces of attraction from the nucleus to the outermost 5s electron, and hence silver is near the bottom of the electrochemical series (E0(Ag+/Ag) = +0.799 V).[10] In group 11, silver has the lowest first ionization energy (showing the instability of the 5s orbital), but has higher second and third ionization energies than copper and gold (showing the stability of the 4d orbitals), so that the chemistry of silver is predominantly that of the +1 oxidation state, reflecting the increasingly limited range of oxidation states along the transition series as the d-orbitals fill and stabilize.[28] Unlike copper, for which the larger hydration energy of Cu2+ as compared to Cu+ is the reason why the former is the more stable in aqueous solution and solids despite lacking the stable filled d-subshell of the latter, with silver this effect is swamped by its larger second ionisation energy. Hence, Ag+ is the stable species in aqueous solution and solids, with Ag2+ being much less stable as it oxidizes water.[28]

Most silver compounds have significant covalent character due to the small size and high first ionization energy (730.8 kJ/mol) of silver.[10] Furthermore, silver's Pauling electronegativity of 1.93 is higher than that of lead (1.87), and its electron affinity of 125.6 kJ/mol is much higher than that of hydrogen (72.8 kJ/mol) and not much less than that of oxygen (141.0 kJ/mol).[29] Due to its full d-subshell, silver in its main +1 oxidation state exhibits relatively few properties of the transition metals proper from groups 4 to 10, forming rather unstable organometallic compounds, forming linear complexes showing very low coordination numbers like 2, and forming an amphoteric oxide[30] as well as Zintl phases like the post-transition metals.[31] Unlike the preceding transition metals, the +1 oxidation state of silver is stable even in the absence of π-acceptor ligands.[28]

Silver does not react with air, even at red heat, and thus was considered by alchemists as a noble metal, along with gold. Its reactivity is intermediate between that of copper (which forms copper(I) oxide when heated in air to red heat) and gold. Like copper, silver reacts with sulfur and its compounds; in their presence, silver tarnishes in air to form the black silver sulfide (copper forms the green sulfate instead, while gold does not react). Unlike copper, silver will not react with the halogens, with the exception of fluorine gas, with which it forms the difluoride. While silver is not attacked by non-oxidizing acids, the metal dissolves readily in hot concentrated sulfuric acid, as well as dilute or concentrated nitric acid. In the presence of air, and especially in the presence of hydrogen peroxide, silver dissolves readily in aqueous solutions of cyanide.[27]

The three main forms of deterioration in historical silver artifacts are tarnishing, formation of silver chloride due to long-term immersion in salt water, as well as reaction with nitrate ions or oxygen. Fresh silver chloride is pale yellow, becoming purplish on exposure to light; it projects slightly from the surface of the artifact or coin. The precipitation of copper in ancient silver can be used to date artifacts, as copper is nearly always a constituent of silver alloys.[32]

Silver metal is attacked by strong oxidizers such as potassium permanganate (KMnO
4
) and potassium dichromate (K
2
Cr
2
O
7
), and in the presence of potassium bromide (KBr). These compounds are used in photography to bleach silver images, converting them to silver bromide that can either be fixed with thiosulfate or redeveloped to intensify the original image. Silver forms cyanide complexes (silver cyanide) that are soluble in water in the presence of an excess of cyanide ions. Silver cyanide solutions are used in electroplating of silver.[33]

The common oxidation states of silver are (in order of commonness): +1 (the most stable state; for example, silver nitrate, AgNO3); +2 (highly oxidising; for example, silver(II) fluoride, AgF2); and even very rarely +3 (extreme oxidising; for example, potassium tetrafluoroargentate(III), KAgF4).[34] The +3 state requires very strong oxidising agents to attain, such as fluorine or peroxodisulfate, and some silver(III) compounds react with atmospheric moisture and attack glass.[35] Indeed, silver(III) fluoride is usually obtained by reacting silver or silver monofluoride with the strongest known oxidizing agent, krypton difluoride.[36]

Compounds

Oxides and chalcogenides

 
Silver(I) sulfide

Silver and gold have rather low chemical affinities for oxygen, lower than copper, and it is therefore expected that silver oxides are thermally quite unstable. Soluble silver(I) salts precipitate dark-brown silver(I) oxide, Ag2O, upon the addition of alkali. (The hydroxide AgOH exists only in solution; otherwise it spontaneously decomposes to the oxide.) Silver(I) oxide is very easily reduced to metallic silver, and decomposes to silver and oxygen above 160 °C.[37] This and other silver(I) compounds may be oxidized by the strong oxidizing agent peroxodisulfate to black AgO, a mixed silver(I,III) oxide of formula AgIAgIIIO2. Some other mixed oxides with silver in non-integral oxidation states, namely Ag2O3 and Ag3O4, are also known, as is Ag3O which behaves as a metallic conductor.[37]

Silver(I) sulfide, Ag2S, is very readily formed from its constituent elements and is the cause of the black tarnish on some old silver objects. It may also be formed from the reaction of hydrogen sulfide with silver metal or aqueous Ag+ ions. Many non-stoichiometric selenides and tellurides are known; in particular, AgTe~3 is a low-temperature superconductor.[37]

Halides

 
The three common silver halide precipitates: from left to right, silver iodide, silver bromide, and silver chloride.

The only known dihalide of silver is the difluoride, AgF2, which can be obtained from the elements under heat. A strong yet thermally stable and therefore safe fluorinating agent, silver(II) fluoride is often used to synthesize hydrofluorocarbons.[38]

In stark contrast to this, all four silver(I) halides are known. The fluoride, chloride, and bromide have the sodium chloride structure, but the iodide has three known stable forms at different temperatures; that at room temperature is the cubic zinc blende structure. They can all be obtained by the direct reaction of their respective elements.[38] As the halogen group is descended, the silver halide gains more and more covalent character, solubility decreases, and the color changes from the white chloride to the yellow iodide as the energy required for ligand-metal charge transfer (XAg+ → XAg) decreases.[38] The fluoride is anomalous, as the fluoride ion is so small that it has a considerable solvation energy and hence is highly water-soluble and forms di- and tetrahydrates.[38] The other three silver halides are highly insoluble in aqueous solutions and are very commonly used in gravimetric analytical methods.[20] All four are photosensitive (though the monofluoride is so only to ultraviolet light), especially the bromide and iodide which photodecompose to silver metal, and thus were used in traditional photography.[38] The reaction involved is:[39]

X + → X + e (excitation of the halide ion, which gives up its extra electron into the conduction band)
Ag+ + e → Ag (liberation of a silver ion, which gains an electron to become a silver atom)

The process is not reversible because the silver atom liberated is typically found at a crystal defect or an impurity site, so that the electron's energy is lowered enough that it is "trapped".[39]

Other inorganic compounds

Silver crystals forming on a copper surface in a silver nitrate solution. Video by Maxim Bilovitskiy
 
Crystals of silver nitrate

White silver nitrate, AgNO3, is a versatile precursor to many other silver compounds, especially the halides, and is much less sensitive to light. It was once called lunar caustic because silver was called luna by the ancient alchemists, who believed that silver was associated with the Moon.[40][41] It is often used for gravimetric analysis, exploiting the insolubility of the heavier silver halides which it is a common precursor to.[20] Silver nitrate is used in many ways in organic synthesis, e.g. for deprotection and oxidations. Ag+ binds alkenes reversibly, and silver nitrate has been used to separate mixtures of alkenes by selective absorption. The resulting adduct can be decomposed with ammonia to release the free alkene.[42]

Yellow silver carbonate, Ag2CO3 can be easily prepared by reacting aqueous solutions of sodium carbonate with a deficiency of silver nitrate.[43] Its principal use is for the production of silver powder for use in microelectronics. It is reduced with formaldehyde, producing silver free of alkali metals:[44]

Ag2CO3 + CH2O → 2 Ag + 2 CO2 + H2

Silver carbonate is also used as a reagent in organic synthesis such as the Koenigs-Knorr reaction. In the Fétizon oxidation, silver carbonate on celite acts as an oxidising agent to form lactones from diols. It is also employed to convert alkyl bromides into alcohols.[43]

Silver fulminate, AgCNO, a powerful, touch-sensitive explosive used in percussion caps, is made by reaction of silver metal with nitric acid in the presence of ethanol. Other dangerously explosive silver compounds are silver azide, AgN3, formed by reaction of silver nitrate with sodium azide,[45] and silver acetylide, Ag2C2, formed when silver reacts with acetylene gas in ammonia solution.[28] In its most characteristic reaction, silver azide decomposes explosively, releasing nitrogen gas: given the photosensitivity of silver salts, this behaviour may be induced by shining a light on its crystals.[28]

2 AgN
3
(s) → 3 N
2
(g) + 2 Ag (s)

Coordination compounds

 
Structure of the diamminesilver(I) complex, [Ag(NH3)2]+

Silver complexes tend to be similar to those of its lighter homologue copper. Silver(III) complexes tend to be rare and very easily reduced to the more stable lower oxidation states, though they are slightly more stable than those of copper(III). For instance, the square planar periodate [Ag(IO5OH)2]5− and tellurate [Ag{TeO4(OH)2}2]5− complexes may be prepared by oxidising silver(I) with alkaline peroxodisulfate. The yellow diamagnetic [AgF4] is much less stable, fuming in moist air and reacting with glass.[35]

Silver(II) complexes are more common. Like the valence isoelectronic copper(II) complexes, they are usually square planar and paramagnetic, which is increased by the greater field splitting for 4d electrons than for 3d electrons. Aqueous Ag2+, produced by oxidation of Ag+ by ozone, is a very strong oxidising agent, even in acidic solutions: it is stabilized in phosphoric acid due to complex formation. Peroxodisulfate oxidation is generally necessary to give the more stable complexes with heterocyclic amines, such as [Ag(py)4]2+ and [Ag(bipy)2]2+: these are stable provided the counterion cannot reduce the silver back to the +1 oxidation state. [AgF4]2− is also known in its violet barium salt, as are some silver(II) complexes with N- or O-donor ligands such as pyridine carboxylates.[46]

By far the most important oxidation state for silver in complexes is +1. The Ag+ cation is diamagnetic, like its homologues Cu+ and Au+, as all three have closed-shell electron configurations with no unpaired electrons: its complexes are colourless provided the ligands are not too easily polarized such as I. Ag+ forms salts with most anions, but it is reluctant to coordinate to oxygen and thus most of these salts are insoluble in water: the exceptions are the nitrate, perchlorate, and fluoride. The tetracoordinate tetrahedral aqueous ion [Ag(H2O)4]+ is known, but the characteristic geometry for the Ag+ cation is 2-coordinate linear. For example, silver chloride dissolves readily in excess aqueous ammonia to form [Ag(NH3)2]+; silver salts are dissolved in photography due to the formation of the thiosulfate complex [Ag(S2O3)2]3−; and cyanide extraction for silver (and gold) works by the formation of the complex [Ag(CN)2]. Silver cyanide forms the linear polymer {Ag–C≡N→Ag–C≡N→}; silver thiocyanate has a similar structure, but forms a zigzag instead because of the sp3-hybridized sulfur atom. Chelating ligands are unable to form linear complexes and thus silver(I) complexes with them tend to form polymers; a few exceptions exist, such as the near-tetrahedral diphosphine and diarsine complexes [Ag(L–L)2]+.[47]

Organometallic

Under standard conditions, silver does not form simple carbonyls, due to the weakness of the Ag–C bond. A few are known at very low temperatures around 6–15 K, such as the green, planar paramagnetic Ag(CO)3, which dimerizes at 25–30 K, probably by forming Ag–Ag bonds. Additionally, the silver carbonyl [Ag(CO)] [B(OTeF5)4] is known. Polymeric AgLX complexes with alkenes and alkynes are known, but their bonds are thermodynamically weaker than even those of the platinum complexes (though they are formed more readily than those of the analogous gold complexes): they are also quite unsymmetrical, showing the weak π bonding in group 11. Ag–C σ bonds may also be formed by silver(I), like copper(I) and gold(I), but the simple alkyls and aryls of silver(I) are even less stable than those of copper(I) (which tend to explode under ambient conditions). For example, poor thermal stability is reflected in the relative decomposition temperatures of AgMe (−50 °C) and CuMe (−15 °C) as well as those of PhAg (74 °C) and PhCu (100 °C).[48]

The C–Ag bond is stabilized by perfluoroalkyl ligands, for example in AgCF(CF3)2.[49] Alkenylsilver compounds are also more stable than their alkylsilver counterparts.[50] Silver-NHC complexes are easily prepared, and are commonly used to prepare other NHC complexes by displacing labile ligands. For example, the reaction of the bis(NHC)silver(I) complex with bis(acetonitrile)palladium dichloride or chlorido(dimethyl sulfide)gold(I):[51]

 

Intermetallic

 
Different colors of silver–copper–gold alloys

Silver forms alloys with most other elements on the periodic table. The elements from groups 1–3, except for hydrogen, lithium, and beryllium, are very miscible with silver in the condensed phase and form intermetallic compounds; those from groups 4–9 are only poorly miscible; the elements in groups 10–14 (except boron and carbon) have very complex Ag–M phase diagrams and form the most commercially important alloys; and the remaining elements on the periodic table have no consistency in their Ag–M phase diagrams. By far the most important such alloys are those with copper: most silver used for coinage and jewellery is in reality a silver–copper alloy, and the eutectic mixture is used in vacuum brazing. The two metals are completely miscible as liquids but not as solids; their importance in industry comes from the fact that their properties tend to be suitable over a wide range of variation in silver and copper concentration, although most useful alloys tend to be richer in silver than the eutectic mixture (71.9% silver and 28.1% copper by weight, and 60.1% silver and 28.1% copper by atom).[52]

Most other binary alloys are of little use: for example, silver–gold alloys are too soft and silver–cadmium alloys too toxic. Ternary alloys have much greater importance: dental amalgams are usually silver–tin–mercury alloys, silver–copper–gold alloys are very important in jewellery (usually on the gold-rich side) and have a vast range of hardnesses and colours, silver–copper–zinc alloys are useful as low-melting brazing alloys, and silver–cadmium–indium (involving three adjacent elements on the periodic table) is useful in nuclear reactors because of its high thermal neutron capture cross-section, good conduction of heat, mechanical stability, and resistance to corrosion in hot water.[52]

Etymology

The word "silver" appears in Old English in various spellings, such as seolfor and siolfor. It is cognate with Old High German silabar; Gothic silubr; or Old Norse silfr, all ultimately deriving from Proto-Germanic *silubra. The Balto-Slavic words for silver are rather similar to the Germanic ones (e.g. Russian серебро [serebró], Polish srebro, Lithuanian sidãbras), as is the Celtiberian form silabur. They may have a common Indo-European origin, although their morphology rather suggest a non-Indo-European Wanderwort.[53][54] Some scholars have thus proposed a Paleo-Hispanic origin, pointing to the Basque form zilharr as an evidence.[55]

The chemical symbol Ag is from the Latin word for "silver", argentum (compare Ancient Greek ἄργυρος, árgyros), from the Proto-Indo-European root *h₂erǵ- (formerly reconstructed as *arǵ-), meaning "white" or "shining". This was the usual Proto-Indo-European word for the metal, whose reflexes are missing in Germanic and Balto-Slavic.[54]

History

 
Silver vase, circa 2400 BC

Silver was one of the seven metals of antiquity that were known to prehistoric humans and whose discovery is thus lost to history.[56] In particular, the three metals of group 11, copper, silver, and gold, occur in the elemental form in nature and were probably used as the first primitive forms of money as opposed to simple bartering.[57] However, unlike copper, silver did not lead to the growth of metallurgy on account of its low structural strength, and was more often used ornamentally or as money.[58] Since silver is more reactive than gold, supplies of native silver were much more limited than those of gold.[57] For example, silver was more expensive than gold in Egypt until around the fifteenth century BC:[59] the Egyptians are thought to have separated gold from silver by heating the metals with salt, and then reducing the silver chloride produced to the metal.[60]

The situation changed with the discovery of cupellation, a technique that allowed silver metal to be extracted from its ores. While 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,[9] and one of the earliest silver extraction centres in Europe was Sardinia in the early Chalcolithic period,[61] these techniques did not spread widely until later, when it spread throughout the region and beyond.[59] The origins of silver production in India, China, and Japan were almost certainly equally ancient, but are not well-documented due to their great age.[60]

 
Silver mining and processing in Kutná Hora, Bohemia, 1490s

When the Phoenicians first came to what is now Spain, they obtained so much silver that they could not fit it all on their ships, and as a result used silver to weight their anchors instead of lead.[59] By the time of the Greek and Roman civilizations, silver coins were a staple of the economy:[57] the Greeks were already extracting silver from galena by the 7th century BC,[59] and the rise of Athens was partly made possible by the nearby silver mines at Laurium, from which they extracted about 30 tonnes a year from 600 to 300 BC.[62] The stability of the Roman currency relied to a high degree on the supply of silver bullion, mostly from Spain, which Roman miners produced on a scale unparalleled before the discovery of the New World. Reaching a peak production of 200 tonnes per year, an estimated silver stock of 10,000 tonnes circulated in the Roman economy in the middle of the second century AD, five to ten times larger than the combined amount of silver available to medieval Europe and the Abbasid Caliphate around AD 800.[63][64] The Romans also recorded the extraction of silver in central and northern Europe in the same time period. This production came to a nearly complete halt with the fall of the Roman Empire, not to resume until the time of Charlemagne: by then, tens of thousands of tonnes of silver had already been extracted.[60]

Central Europe became the centre of silver production during the Middle Ages, as the Mediterranean deposits exploited by the ancient civilisations had been exhausted. Silver mines were opened in Bohemia, Saxony, Erzgebirge, Alsace, the Lahn region, Siegerland, Silesia, Hungary, Norway, Steiermark, Schwaz, and the southern Black Forest. Most of these ores were quite rich in silver and could simply be separated by hand from the remaining rock and then smelted; some deposits of native silver were also encountered. Many of these mines were soon exhausted, but a few of them remained active until the Industrial Revolution, before which the world production of silver was around a meagre 50 tonnes per year.[60] In the Americas, high temperature silver-lead cupellation technology was developed by pre-Inca civilizations as early as AD 60–120; silver deposits in India, China, Japan, and pre-Columbian America continued to be mined during this time.[60][65]

With the discovery of America and the plundering of silver by the Spanish conquistadors, Central and South America became the dominant producers of silver until around the beginning of the 18th century, particularly Peru, Bolivia, Chile, and Argentina:[60] the last of these countries later took its name from that of the metal that composed so much of its mineral wealth.[62] The silver trade gave way to a global network of exchange. As one historian put it, silver "went round the world and made the world go round."[66] Much of this silver ended up in the hands of the Chinese. A Portuguese merchant in 1621 noted that silver "wanders throughout all the world... before flocking to China, where it remains as if at its natural center."[67] Still, much of it went to Spain, allowing Spanish rulers to pursue military and political ambitions in both Europe and the Americas. "New World mines," concluded several historians, "supported the Spanish empire."[68]

In the 19th century, primary production of silver moved to North America, particularly Canada, Mexico, and Nevada in the United States: some secondary production from lead and zinc ores also took place in Europe, and deposits in Siberia and the Russian Far East as well as in Australia were mined.[60] Poland emerged as an important producer during the 1970s after the discovery of copper deposits that were rich in silver, before the centre of production returned to the Americas the following decade. Today, Peru and Mexico are still among the primary silver producers, but the distribution of silver production around the world is quite balanced and about one-fifth of the silver supply comes from recycling instead of new production.[60]

Symbolic role

 
16th-century fresco painting of Judas being paid thirty pieces of silver for his betrayal of Jesus

Silver plays a certain role in mythology and has found various usage as a metaphor and in folklore. The Greek poet Hesiod's Works and Days (lines 109–201) lists different ages of man named after metals like gold, silver, bronze and iron to account for successive ages of humanity.[69] Ovid's Metamorphoses contains another retelling of the story, containing an illustration of silver's metaphorical use of signifying the second-best in a series, better than bronze but worse than gold:

But when good Saturn, banish'd from above,
Was driv'n to Hell, the world was under Jove.
Succeeding times a silver age behold,
Excelling brass, but more excell'd by gold.

— Ovid, Metamorphoses, Book I, trans. John Dryden

In folklore, silver was commonly thought to have mystic powers: for example, a bullet cast from silver is often supposed in such folklore the only weapon that is effective against a werewolf, witch, or other monsters.[70][71][72] From this the idiom of a silver bullet developed into figuratively referring to any simple solution with very high effectiveness or almost miraculous results, as in the widely discussed software engineering paper No Silver Bullet.[73] Other powers attributed to silver include detection of poison and facilitation of passage into the mythical realm of fairies.[72]

Silver production has also inspired figurative language. Clear references to cupellation occur throughout the Old Testament of the Bible, such as in Jeremiah's rebuke to Judah: "The bellows are burned, the lead is consumed of the fire; the founder melteth in vain: for the wicked are not plucked away. Reprobate silver shall men call them, because the Lord hath rejected them." (Jeremiah 6:19–20) Jeremiah was also aware of sheet silver, exemplifying the malleability and ductility of the metal: "Silver spread into plates is brought from Tarshish, and gold from Uphaz, the work of the workman, and of the hands of the founder: blue and purple is their clothing: they are all the work of cunning men." (Jeremiah 10:9)[59]

Silver also has more negative cultural meanings: the idiom thirty pieces of silver, referring to a reward for betrayal, references the bribe Judas Iscariot is said in the New Testament to have taken from Jewish leaders in Jerusalem to turn Jesus of Nazareth over to soldiers of the high priest Caiaphas.[74] Ethically, silver also symbolizes greed and degradation of consciousness; this is the negative aspect, the perverting of its value.[75]

Occurrence and production

 
World production of silver

The abundance of silver in the Earth's crust is 0.08 parts per million, almost exactly the same as that of mercury. It mostly occurs in sulfide ores, especially acanthite and argentite, Ag2S. Argentite deposits sometimes also contain native silver when they occur in reducing environments, and when in contact with salt water they are converted to chlorargyrite (including horn silver), AgCl, which is prevalent in Chile and New South Wales.[76] Most other silver minerals are silver pnictides or chalcogenides; they are generally lustrous semiconductors. Most true silver deposits, as opposed to argentiferous deposits of other metals, came from Tertiary period vulcanism.[77]

The principal sources of silver are the ores of copper, copper-nickel, lead, and lead-zinc obtained from Peru, Bolivia, Mexico, China, Australia, Chile, Poland and Serbia.[9] Peru, Bolivia and Mexico have been mining silver since 1546, and are still major world producers. Top silver-producing mines are Cannington (Australia), Fresnillo (Mexico), San Cristóbal (Bolivia), Antamina (Peru), Rudna (Poland), and Penasquito (Mexico).[78] Top near-term mine development projects through 2015 are Pascua Lama (Chile), Navidad (Argentina), Jaunicipio (Mexico), Malku Khota (Bolivia),[79] and Hackett River (Canada).[78] In Central Asia, Tajikistan is known to have some of the largest silver deposits in the world.[80]

Silver is usually found in nature combined with other metals, or in minerals that contain silver compounds, generally in the form of sulfides such as galena (lead sulfide) or cerussite (lead carbonate). So the primary production of silver requires the smelting and then cupellation of argentiferous lead ores, a historically important process.[81] Lead melts at 327 °C, lead oxide at 888 °C and silver melts at 960 °C. To separate the silver, the alloy is melted again at the high temperature of 960 °C to 1000 °C in an oxidizing environment. The lead oxidises to lead monoxide, then known as litharge, which captures the oxygen from the other metals present. The liquid lead oxide is removed or absorbed by capillary action into the hearth linings.[82][83][84]

Ag(s) + 2Pb(s) + O
2
(g) → 2PbO(absorbed) + Ag(l)

Today, silver metal is primarily produced instead as a secondary byproduct of electrolytic refining of copper, lead, and zinc, and by application of the Parkes process on lead bullion from ore that also contains silver.[85] In such processes, silver follows the non-ferrous metal in question through its concentration and smelting, and is later purified out. For example, in copper production, purified copper is electrolytically deposited on the cathode, while the less reactive precious metals such as silver and gold collect under the anode as the so-called "anode slime". This is then separated and purified of base metals by treatment with hot aerated dilute sulfuric acid and heating with lime or silica flux, before the silver is purified to over 99.9% purity via electrolysis in nitrate solution.[76]

Commercial-grade fine silver is at least 99.9% pure, and purities greater than 99.999% are available. In 2022, Mexico was the top producer of silver (6,300 tonnes or 24.2% of the world's total of 26,000 t), followed by China (3,600 t) and Peru (3,100 t).[85]

In marine environments

Silver concentration is low in seawater (pmol/L). Levels vary by depth and between water bodies. Dissolved silver concentrations range from 0.3 pmol/L in coastal surface waters to 22.8 pmol/L in pelagic deep waters.[86] Analyzing the presence and dynamics of silver in marine environments is difficult due to these particularly low concentrations and complex interactions in the environment.[87] Although a rare trace metal, concentrations are greatly impacted by fluvial, aeolian, atmospheric, and upwelling inputs, as well as anthropogenic inputs via discharge, waste disposal, and emissions from industrial companies.[88][89] Other internal processes such as decomposition of organic matter may be a source of dissolved silver in deeper waters, which feeds into some surface waters through upwelling and vertical mixing.[89]

In the Atlantic and Pacific, silver concentrations are minimal at the surface but rise in deeper waters.[90] Silver is taken up by plankton in the photic zone, remobilized with depth, and enriched in deep waters. Silver is transported from the Atlantic to the other oceanic water masses.[88] In North Pacific waters, silver is remobilized at a slower rate and increasingly enriched compared to deep Atlantic waters. Silver has increasing concentrations that follow the major oceanic conveyor belt that cycles water and nutrients from the North Atlantic to the South Atlantic to the North Pacific.[91]

There is not an extensive amount of data focused on how marine life is affected by silver despite the likely deleterious effects it could have on organisms through bioaccumulation, association with particulate matters, and sorption.[86] Not until about 1984 did scientists begin to understand the chemical characteristics of silver and the potential toxicity. In fact, mercury is the only other trace metal that surpasses the toxic effects of silver; however, the full extent of silver toxicity is not expected in oceanic conditions because of its ability to transfer into nonreactive biological compounds.[92]

In one study, the presence of excess ionic silver and silver nanoparticles caused bioaccumulation effects on zebrafish organs and altered the chemical pathways within their gills.[93] In addition, very early experimental studies demonstrated how the toxic effects of silver fluctuate with salinity and other parameters, as well as between life stages and different species such as finfish, molluscs, and crustaceans.[94] Another study found raised concentrations of silver in the muscles and liver of dolphins and whales, indicating pollution of this metal within recent decades. Silver is not an easy metal for an organism to eliminate and elevated concentrations can cause death.[95]

Monetary use

 
A 2004 American Silver Eagle bullion coin, minted in .999 fine silver.

The earliest known coins were minted in the kingdom of Lydia in Asia Minor around 600 BC.[96] The coins of Lydia were made of electrum, which is a naturally occurring alloy of gold and silver, that was available within the territory of Lydia.[96] Since that time, silver standards, in which the standard economic unit of account is a fixed weight of silver, have been widespread throughout the world until the 20th century. Notable silver coins through the centuries include the Greek drachma,[97] the Roman denarius,[98] the Islamic dirham,[99] the karshapana from ancient India and rupee from the time of the Mughal Empire (grouped with copper and gold coins to create a trimetallic standard),[100] and the Spanish dollar.[101]

The ratio between the amount of silver used for coinage and that used for other purposes has fluctuated greatly over time; for example, in wartime, more silver tends to have been used for coinage to finance the war.[102]

Today, silver bullion has the ISO 4217 currency code XAG, one of only four precious metals to have one (the others being palladium, platinum, and gold).[103] Silver coins are produced from cast rods or ingots, rolled to the correct thickness, heat-treated, and then used to cut blanks from. These blanks are then milled and minted in a coining press; modern coining presses can produce 8000 silver coins per hour.[102]

Price

 
Price of silver 1968–2022

Silver prices are normally quoted in troy ounces. One troy ounce is equal to 31.1034768 grams. The London silver fix is published every working day at noon London time.[104] This price is determined by several major international banks and is used by London bullion market members for trading that day. Prices are most commonly shown as the United States dollar (USD), the Pound sterling (GBP), and the Euro (EUR).

Applications

Jewellery and silverware

 
Embossed silver sarcophagus of Saint Stanislaus in the Wawel Cathedral was created in main centers of the 17th century European silversmitheryAugsburg and Gdańsk[105]
 
17th century silverware

The major use of silver besides coinage throughout most of history was in the manufacture of jewellery and other general-use items, and this continues to be a major use today. Examples include table silver for cutlery, for which silver is highly suited due to its antibacterial properties. Western concert flutes are usually plated with or made out of sterling silver;[106] in fact, most silverware is only silver-plated rather than made out of pure silver; the silver is normally put in place by electroplating. Silver-plated glass (as opposed to metal) is used for mirrors, vacuum flasks, and Christmas tree decorations.[107]

Because pure silver is very soft, most silver used for these purposes is alloyed with copper, with finenesses of 925/1000, 835/1000, and 800/1000 being common. One drawback is the easy tarnishing of silver in the presence of hydrogen sulfide and its derivatives. Including precious metals such as palladium, platinum, and gold gives resistance to tarnishing but is quite costly; base metals like zinc, cadmium, silicon, and germanium do not totally prevent corrosion and tend to affect the lustre and colour of the alloy. Electrolytically refined pure silver plating is effective at increasing resistance to tarnishing. The usual solutions for restoring the lustre of tarnished silver are dipping baths that reduce the silver sulfide surface to metallic silver, and cleaning off the layer of tarnish with a paste; the latter approach also has the welcome side effect of polishing the silver concurrently.[106]

Medicine

In medicine, silver is incorporated into wound dressings and used as an antibiotic coating in medical devices. Wound dressings containing silver sulfadiazine or silver nanomaterials are used to treat external infections. Silver is also used in some medical applications, such as urinary catheters (where tentative evidence indicates it reduces catheter-related urinary tract infections) and in endotracheal breathing tubes (where evidence suggests it reduces ventilator-associated pneumonia).[108][109] The silver ion is bioactive and in sufficient concentration readily kills bacteria in vitro. Silver ions interfere with enzymes in the bacteria that transport nutrients, form structures, and synthesise cell walls; these ions also bond with the bacteria's genetic material. Silver and silver nanoparticles are used as an antimicrobial in a variety of industrial, healthcare, and domestic application: for example, infusing clothing with nanosilver particles thus allows them to stay odourless for longer.[110][111] Bacteria can, however, develop resistance to the antimicrobial action of silver.[112] Silver compounds are taken up by the body like mercury compounds, but lack the toxicity of the latter. Silver and its alloys are used in cranial surgery to replace bone, and silver–tin–mercury amalgams are used in dentistry.[107] Silver diammine fluoride, the fluoride salt of a coordination complex with the formula [Ag(NH3)2]F, is a topical medicament (drug) used to treat and prevent dental caries (cavities) and relieve dentinal hypersensitivity.[113]

Electronics

Silver is very important in electronics for conductors and electrodes on account of its high electrical conductivity even when tarnished. Bulk silver and silver foils were used to make vacuum tubes, and continue to be used today in the manufacture of semiconductor devices, circuits, and their components. For example, silver is used in high quality connectors for RF, VHF, and higher frequencies, particularly in tuned circuits such as cavity filters where conductors cannot be scaled by more than 6%. Printed circuits and RFID antennas are made with silver paints,[9][114] Powdered silver and its alloys are used in paste preparations for conductor layers and electrodes, ceramic capacitors, and other ceramic components.[115]

Brazing alloys

Silver-containing brazing alloys are used for brazing metallic materials, mostly cobalt, nickel, and copper-based alloys, tool steels, and precious metals. The basic components are silver and copper, with other elements selected according to the specific application desired: examples include zinc, tin, cadmium, palladium, manganese, and phosphorus. Silver provides increased workability and corrosion resistance during usage.[116]

Chemical equipment

Silver is useful in the manufacture of chemical equipment on account of its low chemical reactivity, high thermal conductivity, and being easily workable. Silver crucibles (alloyed with 0.15% nickel to avoid recrystallisation of the metal at red heat) are used for carrying out alkaline fusion. Copper and silver are also used when doing chemistry with fluorine. Equipment made to work at high temperatures is often silver-plated. Silver and its alloys with gold are used as wire or ring seals for oxygen compressors and vacuum equipment.[117]

Catalysis

Silver metal is a good catalyst for oxidation reactions; in fact it is somewhat too good for most purposes, as finely divided silver tends to result in complete oxidation of organic substances to carbon dioxide and water, and hence coarser-grained silver tends to be used instead. For instance, 15% silver supported on α-Al2O3 or silicates is a catalyst for the oxidation of ethylene to ethylene oxide at 230–270 °C. Dehydrogenation of methanol to formaldehyde is conducted at 600–720 °C over silver gauze or crystals as the catalyst, as is dehydrogenation of isopropanol to acetone. In the gas phase, glycol yields glyoxal and ethanol yields acetaldehyde, while organic amines are dehydrated to nitriles.[117]

Photography

The photosensitivity of the silver halides allowed for their use in traditional photography, although digital photography, which does not use silver, is now dominant. The photosensitive emulsion used in black-and-white photography is a suspension of silver halide crystals in gelatin, possibly mixed in with some noble metal compounds for improved photosensitivity, developing, and tuning[clarify]. Colour photography requires the addition of special dye components and sensitisers, so that the initial black-and-white silver image couples with a different dye component. The original silver images are bleached off and the silver is then recovered and recycled. Silver nitrate is the starting material in all cases.[118]

The use of silver nitrate and silver halides in photography has rapidly declined with the advent of digital technology. From the peak global demand for photographic silver in 1999 (267,000,000 troy ounces or 8,304.6 tonnes) the market contracted almost 70% by 2013.[119]

Nanoparticles

Nanosilver particles, between 10 and 100 nanometres in size, are used in many applications. They are used in conductive inks for printed electronics, and have a much lower melting point than larger silver particles of micrometre size. They are also used medicinally in antibacterials and antifungals in much the same way as larger silver particles.[111] In addition, according to the European Union Observatory for Nanomaterials (EUON), silver nanoparticles are used both in pigments, as well as cosmetics.[120][121]

Miscellanea

 
A tray of South Asian sweets, with some pieces covered with shiny silver vark

Pure silver metal is used as a food colouring. It has the E174 designation and is approved in the European Union.[122] Traditional Indian and Pakistani dishes sometimes include decorative silver foil known as vark,[123] and in various other cultures, silver dragée are used to decorate cakes, cookies, and other dessert items.[124]

Photochromic lenses include silver halides, so that ultraviolet light in natural daylight liberates metallic silver, darkening the lenses. The silver halides are reformed in lower light intensities. Colourless silver chloride films are used in radiation detectors. Zeolite sieves incorporating Ag+ ions are used to desalinate seawater during rescues, using silver ions to precipitate chloride as silver chloride. Silver is also used for its antibacterial properties for water sanitisation, but the application of this is limited by limits on silver consumption. Colloidal silver is similarly used to disinfect closed swimming pools; while it has the advantage of not giving off a smell like hypochlorite treatments do, colloidal silver is not effective enough for more contaminated open swimming pools. Small silver iodide crystals are used in cloud seeding to cause rain.[111]

The Texas Legislature designated silver the official precious metal of Texas in 2007.[125]

Precautions

Silver
Hazards
GHS labelling:
 
Warning
H410
P273, P391, P501[126]
NFPA 704 (fire diamond)
0
0
0

Silver compounds have low toxicity compared to those of most other heavy metals, as they are poorly absorbed by the human body when ingested, and that which does get absorbed is rapidly converted to insoluble silver compounds or complexed by metallothionein. However, silver fluoride and silver nitrate are caustic and can cause tissue damage, resulting in gastroenteritis, diarrhoea, falling blood pressure, cramps, paralysis, and respiratory arrest. Animals repeatedly dosed with silver salts have been observed to experience anaemia, slowed growth, necrosis of the liver, and fatty degeneration of the liver and kidneys; rats implanted with silver foil or injected with colloidal silver have been observed to develop localised tumours. Parenterally admistered colloidal silver causes acute silver poisoning.[127] Some waterborne species are particularly sensitive to silver salts and those of the other precious metals; in most situations, however, silver does not pose serious environmental hazards.[127]

In large doses, silver and compounds containing it can be absorbed into the circulatory system and become deposited in various body tissues, leading to argyria, which results in a blue-grayish pigmentation of the skin, eyes, and mucous membranes. Argyria is rare, and so far as is known, does not otherwise harm a person's health, though it is disfiguring and usually permanent. Mild forms of argyria are sometimes mistaken for cyanosis, a blue tint on skin, caused by lack of oxygen.[127][9]

Metallic silver, like copper, is an antibacterial agent, which was known to the ancients and first scientifically investigated and named the oligodynamic effect by Carl Nägeli. Silver ions damage the metabolism of bacteria even at such low concentrations as 0.01–0.1 milligrams per litre; metallic silver has a similar effect due to the formation of silver oxide. This effect is lost in the presence of sulfur due to the extreme insolubility of silver sulfide.[127]

Some silver compounds are very explosive, such as the nitrogen compounds silver azide, silver amide, and silver fulminate, as well as silver acetylide, silver oxalate, and silver(II) oxide. They can explode on heating, force, drying, illumination, or sometimes spontaneously. To avoid the formation of such compounds, ammonia and acetylene should be kept away from silver equipment. Salts of silver with strongly oxidising acids such as silver chlorate and silver nitrate can explode on contact with materials that can be readily oxidised, such as organic compounds, sulfur and soot.[127]

See also

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  • Silver at The Periodic Table of Videos (University of Nottingham)
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silver, this, article, about, chemical, element, silver, medication, medical, uses, silver, other, uses, disambiguation, chemical, element, with, symbol, from, latin, argentum, derived, from, proto, indo, european, erǵ, shiny, white, atomic, number, soft, whit. This article is about the chemical element For the use of silver as a medication see Medical uses of silver For other uses see Silver disambiguation Silver is a chemical element with the symbol Ag from the Latin argentum derived from the Proto Indo European h erǵ shiny or white and atomic number 47 A soft white lustrous transition metal it exhibits the highest electrical conductivity thermal conductivity and reflectivity of any metal 5 The metal is found in the Earth s crust in the pure free elemental form native silver as an alloy with gold and other metals and in minerals such as argentite and chlorargyrite Most silver is produced as a byproduct of copper gold lead and zinc refining Silver 47AgSilverAppearancelustrous white metalStandard atomic weight Ar Ag 107 8682 0 0002107 87 0 01 abridged 1 Silver in the periodic tableHydrogen HeliumLithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine NeonSodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine ArgonPotassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine KryptonRubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine XenonCaesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury element Thallium Lead Bismuth Polonium Astatine RadonFrancium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Cu Ag Aupalladium silver cadmiumAtomic number Z 47Groupgroup 11Periodperiod 5Block d blockElectron configuration Kr 4d10 5s1Electrons per shell2 8 18 18 1Physical propertiesPhase at STPsolidMelting point1234 93 K 961 78 C 1763 2 F Boiling point2435 K 2162 C 3924 F Density near r t 10 49 g cm3when liquid at m p 9 320 g cm3Heat of fusion11 28 kJ molHeat of vaporisation254 kJ molMolar heat capacity25 350 J mol K Vapour pressureP Pa 1 10 100 1 k 10 k 100 kat T K 1283 1413 1575 1782 2055 2433Atomic propertiesOxidation states 2 1 0 2 1 2 3 an amphoteric oxide ElectronegativityPauling scale 1 93Ionisation energies1st 731 0 kJ mol2nd 2070 kJ mol3rd 3361 kJ molAtomic radiusempirical 144 pmCovalent radius145 5 pmVan der Waals radius172 pmSpectral lines of silverOther propertiesNatural occurrenceprimordialCrystal structure face centred cubic fcc Speed of sound thin rod2680 m s at r t Thermal expansion18 9 µm m K at 25 C Thermal conductivity429 W m K Thermal diffusivity174 mm2 s at 300 K Electrical resistivity15 87 nW m at 20 C Magnetic orderingdiamagnetic 3 Molar magnetic susceptibility 19 5 10 6 cm3 mol 296 K 4 Young s modulus83 GPaShear modulus30 GPaBulk modulus100 GPaPoisson ratio0 37Mohs hardness2 5Vickers hardness251 MPaBrinell hardness206 250 MPaCAS Number7440 22 4HistoryDiscoverybefore 5000 BCSymbol Ag from Latin argentumIsotopes of silverveMain isotopes Decayabun dance half life t1 2 mode pro duct105Ag syn 41 3 d e 105Pdg 106mAg syn 8 28 d e 106Pdg 107Ag 51 839 stable108mAg syn 439 y e 108PdIT 108Agg 109Ag 48 161 stable110m2Ag syn 249 86 d b 110Cdg 111Ag syn 7 43 d b 111Cdg Category Silverviewtalkedit referencesSilver has long been valued as a precious metal Silver metal is used in many bullion coins sometimes alongside gold 6 while it is more abundant than gold it is much less abundant as a native metal 7 Its purity is typically measured on a per mille basis a 94 pure alloy is described as 0 940 fine As one of the seven metals of antiquity silver has had an enduring role in most human cultures Other than in currency and as an investment medium coins and bullion silver is used in solar panels water filtration jewellery ornaments high value tableware and utensils hence the term silverware in electrical contacts and conductors in specialized mirrors window coatings in catalysis of chemical reactions as a colorant in stained glass and in specialized confectionery Its compounds are used in photographic and X ray film Dilute solutions of silver nitrate and other silver compounds are used as disinfectants and microbiocides oligodynamic effect added to bandages wound dressings catheters and other medical instruments Contents 1 Characteristics 1 1 Isotopes 2 Chemistry 3 Compounds 3 1 Oxides and chalcogenides 3 2 Halides 3 3 Other inorganic compounds 3 4 Coordination compounds 3 5 Organometallic 3 6 Intermetallic 4 Etymology 5 History 6 Symbolic role 7 Occurrence and production 7 1 In marine environments 8 Monetary use 8 1 Price 9 Applications 9 1 Jewellery and silverware 9 2 Medicine 9 3 Electronics 9 4 Brazing alloys 9 5 Chemical equipment 9 6 Catalysis 9 7 Photography 9 8 Nanoparticles 9 9 Miscellanea 10 Precautions 11 See also 12 References 13 Cited sources 14 External linksCharacteristics Silver is extremely ductile and can be drawn into a wire one atom wide 8 Silver is similar in its physical and chemical properties to its two vertical neighbours in group 11 of the periodic table copper and gold Its 47 electrons are arranged in the configuration Kr 4d105s1 similarly to copper Ar 3d104s1 and gold Xe 4f145d106s1 group 11 is one of the few groups in the d block which has a completely consistent set of electron configurations 9 This distinctive electron configuration with a single electron in the highest occupied s subshell over a filled d subshell accounts for many of the singular properties of metallic silver 10 Silver is a relatively soft and extremely ductile and malleable transition metal though it is slightly less malleable than gold Silver crystallizes in a face centered cubic lattice with bulk coordination number 12 where only the single 5s electron is delocalized similarly to copper and gold 11 Unlike metals with incomplete d shells metallic bonds in silver are lacking a covalent character and are relatively weak This observation explains the low hardness and high ductility of single crystals of silver 12 Silver has a brilliant white metallic luster that can take a high polish 13 and which is so characteristic that the name of the metal itself has become a colour name 10 Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than 450 nm 14 At wavelengths shorter than 450 nm silver s reflectivity is inferior to that of aluminium and drops to zero near 310 nm 15 Very high electrical and thermal conductivity are common to the elements in group 11 because their single s electron is free and does not interact with the filled d subshell as such interactions which occur in the preceding transition metals lower electron mobility 16 The thermal conductivity of silver is among the highest of all materials although the thermal conductivity of carbon in the diamond allotrope and superfluid helium 4 are higher 9 The electrical conductivity of silver is the highest of all metals greater even than copper Silver also has the lowest contact resistance of any metal 9 Silver is rarely used for its electrical conductivity due to its high cost although an exception is in radio frequency engineering particularly at VHF and higher frequencies where silver plating improves electrical conductivity because those currents tend to flow on the surface of conductors rather than through the interior During World War II in the US 13540 tons of silver were used for the electromagnets in calutrons for enriching uranium mainly because of the wartime shortage of copper 17 18 19 Silver readily forms alloys with copper gold and zinc Zinc silver alloys with low zinc concentration may be considered as face centred cubic solid solutions of zinc in silver as the structure of the silver is largely unchanged while the electron concentration rises as more zinc is added Increasing the electron concentration further leads to body centred cubic electron concentration 1 5 complex cubic 1 615 and hexagonal close packed phases 1 75 11 Isotopes Main article Isotopes of silver Naturally occurring silver is composed of two stable isotopes 107Ag and 109Ag with 107Ag being slightly more abundant 51 839 natural abundance This almost equal abundance is rare in the periodic table The atomic weight is 107 8682 2 u 20 21 this value is very important because of the importance of silver compounds particularly halides in gravimetric analysis 20 Both isotopes of silver are produced in stars via the s process slow neutron capture as well as in supernovas via the r process rapid neutron capture 22 Twenty eight radioisotopes have been characterized the most stable being 105Ag with a half life of 41 29 days 111Ag with a half life of 7 45 days and 112Ag with a half life of 3 13 hours Silver has numerous nuclear isomers the most stable being 108mAg t1 2 418 years 110mAg t1 2 249 79 days and 106mAg t1 2 8 28 days All of the remaining radioactive isotopes have half lives of less than an hour and the majority of these have half lives of less than three minutes 23 Isotopes of silver range in relative atomic mass from 92 950 u 93Ag to 129 950 u 130Ag 24 the primary decay mode before the most abundant stable isotope 107Ag is electron capture and the primary mode after is beta decay The primary decay products before 107Ag are palladium element 46 isotopes and the primary products after are cadmium element 48 isotopes 23 The palladium isotope 107Pd decays by beta emission to 107Ag with a half life of 6 5 million years Iron meteorites are the only objects with a high enough palladium to silver ratio to yield measurable variations in 107Ag abundance Radiogenic 107Ag was first discovered in the Santa Clara meteorite in 1978 25 107Pd 107Ag correlations observed in bodies that have clearly been melted since the accretion of the Solar System must reflect the presence of unstable nuclides in the early Solar System 26 ChemistryOxidation states and stereochemistries of silver 27 Oxidation state Coordination number Stereochemistry Representativecompound0 d10s1 3 Planar Ag CO 31 d10 2 Linear Ag CN 2 3 Trigonal planar AgI PEt2Ar 24 Tetrahedral Ag diars 2 6 Octahedral AgF AgCl AgBr2 d9 4 Square planar Ag py 4 2 3 d8 4 Square planar AgF4 6 Octahedral AgF6 3 Silver is a rather unreactive metal This is because its filled 4d shell is not very effective in shielding the electrostatic forces of attraction from the nucleus to the outermost 5s electron and hence silver is near the bottom of the electrochemical series E0 Ag Ag 0 799 V 10 In group 11 silver has the lowest first ionization energy showing the instability of the 5s orbital but has higher second and third ionization energies than copper and gold showing the stability of the 4d orbitals so that the chemistry of silver is predominantly that of the 1 oxidation state reflecting the increasingly limited range of oxidation states along the transition series as the d orbitals fill and stabilize 28 Unlike copper for which the larger hydration energy of Cu2 as compared to Cu is the reason why the former is the more stable in aqueous solution and solids despite lacking the stable filled d subshell of the latter with silver this effect is swamped by its larger second ionisation energy Hence Ag is the stable species in aqueous solution and solids with Ag2 being much less stable as it oxidizes water 28 Most silver compounds have significant covalent character due to the small size and high first ionization energy 730 8 kJ mol of silver 10 Furthermore silver s Pauling electronegativity of 1 93 is higher than that of lead 1 87 and its electron affinity of 125 6 kJ mol is much higher than that of hydrogen 72 8 kJ mol and not much less than that of oxygen 141 0 kJ mol 29 Due to its full d subshell silver in its main 1 oxidation state exhibits relatively few properties of the transition metals proper from groups 4 to 10 forming rather unstable organometallic compounds forming linear complexes showing very low coordination numbers like 2 and forming an amphoteric oxide 30 as well as Zintl phases like the post transition metals 31 Unlike the preceding transition metals the 1 oxidation state of silver is stable even in the absence of p acceptor ligands 28 Silver does not react with air even at red heat and thus was considered by alchemists as a noble metal along with gold Its reactivity is intermediate between that of copper which forms copper I oxide when heated in air to red heat and gold Like copper silver reacts with sulfur and its compounds in their presence silver tarnishes in air to form the black silver sulfide copper forms the green sulfate instead while gold does not react Unlike copper silver will not react with the halogens with the exception of fluorine gas with which it forms the difluoride While silver is not attacked by non oxidizing acids the metal dissolves readily in hot concentrated sulfuric acid as well as dilute or concentrated nitric acid In the presence of air and especially in the presence of hydrogen peroxide silver dissolves readily in aqueous solutions of cyanide 27 The three main forms of deterioration in historical silver artifacts are tarnishing formation of silver chloride due to long term immersion in salt water as well as reaction with nitrate ions or oxygen Fresh silver chloride is pale yellow becoming purplish on exposure to light it projects slightly from the surface of the artifact or coin The precipitation of copper in ancient silver can be used to date artifacts as copper is nearly always a constituent of silver alloys 32 Silver metal is attacked by strong oxidizers such as potassium permanganate KMnO4 and potassium dichromate K2 Cr2 O7 and in the presence of potassium bromide KBr These compounds are used in photography to bleach silver images converting them to silver bromide that can either be fixed with thiosulfate or redeveloped to intensify the original image Silver forms cyanide complexes silver cyanide that are soluble in water in the presence of an excess of cyanide ions Silver cyanide solutions are used in electroplating of silver 33 The common oxidation states of silver are in order of commonness 1 the most stable state for example silver nitrate AgNO3 2 highly oxidising for example silver II fluoride AgF2 and even very rarely 3 extreme oxidising for example potassium tetrafluoroargentate III KAgF4 34 The 3 state requires very strong oxidising agents to attain such as fluorine or peroxodisulfate and some silver III compounds react with atmospheric moisture and attack glass 35 Indeed silver III fluoride is usually obtained by reacting silver or silver monofluoride with the strongest known oxidizing agent krypton difluoride 36 CompoundsOxides and chalcogenides Silver I sulfide Silver and gold have rather low chemical affinities for oxygen lower than copper and it is therefore expected that silver oxides are thermally quite unstable Soluble silver I salts precipitate dark brown silver I oxide Ag2O upon the addition of alkali The hydroxide AgOH exists only in solution otherwise it spontaneously decomposes to the oxide Silver I oxide is very easily reduced to metallic silver and decomposes to silver and oxygen above 160 C 37 This and other silver I compounds may be oxidized by the strong oxidizing agent peroxodisulfate to black AgO a mixed silver I III oxide of formula AgIAgIIIO2 Some other mixed oxides with silver in non integral oxidation states namely Ag2O3 and Ag3O4 are also known as is Ag3O which behaves as a metallic conductor 37 Silver I sulfide Ag2S is very readily formed from its constituent elements and is the cause of the black tarnish on some old silver objects It may also be formed from the reaction of hydrogen sulfide with silver metal or aqueous Ag ions Many non stoichiometric selenides and tellurides are known in particular AgTe 3 is a low temperature superconductor 37 Halides Main article Silver halide The three common silver halide precipitates from left to right silver iodide silver bromide and silver chloride The only known dihalide of silver is the difluoride AgF2 which can be obtained from the elements under heat A strong yet thermally stable and therefore safe fluorinating agent silver II fluoride is often used to synthesize hydrofluorocarbons 38 In stark contrast to this all four silver I halides are known The fluoride chloride and bromide have the sodium chloride structure but the iodide has three known stable forms at different temperatures that at room temperature is the cubic zinc blende structure They can all be obtained by the direct reaction of their respective elements 38 As the halogen group is descended the silver halide gains more and more covalent character solubility decreases and the color changes from the white chloride to the yellow iodide as the energy required for ligand metal charge transfer X Ag XAg decreases 38 The fluoride is anomalous as the fluoride ion is so small that it has a considerable solvation energy and hence is highly water soluble and forms di and tetrahydrates 38 The other three silver halides are highly insoluble in aqueous solutions and are very commonly used in gravimetric analytical methods 20 All four are photosensitive though the monofluoride is so only to ultraviolet light especially the bromide and iodide which photodecompose to silver metal and thus were used in traditional photography 38 The reaction involved is 39 X hn X e excitation of the halide ion which gives up its extra electron into the conduction band Ag e Ag liberation of a silver ion which gains an electron to become a silver atom The process is not reversible because the silver atom liberated is typically found at a crystal defect or an impurity site so that the electron s energy is lowered enough that it is trapped 39 Other inorganic compounds source source source source source source source source source source source source source source Silver crystals forming on a copper surface in a silver nitrate solution Video by Maxim Bilovitskiy Crystals of silver nitrate White silver nitrate AgNO3 is a versatile precursor to many other silver compounds especially the halides and is much less sensitive to light It was once called lunar caustic because silver was called luna by the ancient alchemists who believed that silver was associated with the Moon 40 41 It is often used for gravimetric analysis exploiting the insolubility of the heavier silver halides which it is a common precursor to 20 Silver nitrate is used in many ways in organic synthesis e g for deprotection and oxidations Ag binds alkenes reversibly and silver nitrate has been used to separate mixtures of alkenes by selective absorption The resulting adduct can be decomposed with ammonia to release the free alkene 42 Yellow silver carbonate Ag2CO3 can be easily prepared by reacting aqueous solutions of sodium carbonate with a deficiency of silver nitrate 43 Its principal use is for the production of silver powder for use in microelectronics It is reduced with formaldehyde producing silver free of alkali metals 44 Ag2CO3 CH2O 2 Ag 2 CO2 H2Silver carbonate is also used as a reagent in organic synthesis such as the Koenigs Knorr reaction In the Fetizon oxidation silver carbonate on celite acts as an oxidising agent to form lactones from diols It is also employed to convert alkyl bromides into alcohols 43 Silver fulminate AgCNO a powerful touch sensitive explosive used in percussion caps is made by reaction of silver metal with nitric acid in the presence of ethanol Other dangerously explosive silver compounds are silver azide AgN3 formed by reaction of silver nitrate with sodium azide 45 and silver acetylide Ag2C2 formed when silver reacts with acetylene gas in ammonia solution 28 In its most characteristic reaction silver azide decomposes explosively releasing nitrogen gas given the photosensitivity of silver salts this behaviour may be induced by shining a light on its crystals 28 2 AgN3 s 3 N2 g 2 Ag s Coordination compounds Structure of the diamminesilver I complex Ag NH3 2 Silver complexes tend to be similar to those of its lighter homologue copper Silver III complexes tend to be rare and very easily reduced to the more stable lower oxidation states though they are slightly more stable than those of copper III For instance the square planar periodate Ag IO5OH 2 5 and tellurate Ag TeO4 OH 2 2 5 complexes may be prepared by oxidising silver I with alkaline peroxodisulfate The yellow diamagnetic AgF4 is much less stable fuming in moist air and reacting with glass 35 Silver II complexes are more common Like the valence isoelectronic copper II complexes they are usually square planar and paramagnetic which is increased by the greater field splitting for 4d electrons than for 3d electrons Aqueous Ag2 produced by oxidation of Ag by ozone is a very strong oxidising agent even in acidic solutions it is stabilized in phosphoric acid due to complex formation Peroxodisulfate oxidation is generally necessary to give the more stable complexes with heterocyclic amines such as Ag py 4 2 and Ag bipy 2 2 these are stable provided the counterion cannot reduce the silver back to the 1 oxidation state AgF4 2 is also known in its violet barium salt as are some silver II complexes with N or O donor ligands such as pyridine carboxylates 46 By far the most important oxidation state for silver in complexes is 1 The Ag cation is diamagnetic like its homologues Cu and Au as all three have closed shell electron configurations with no unpaired electrons its complexes are colourless provided the ligands are not too easily polarized such as I Ag forms salts with most anions but it is reluctant to coordinate to oxygen and thus most of these salts are insoluble in water the exceptions are the nitrate perchlorate and fluoride The tetracoordinate tetrahedral aqueous ion Ag H2O 4 is known but the characteristic geometry for the Ag cation is 2 coordinate linear For example silver chloride dissolves readily in excess aqueous ammonia to form Ag NH3 2 silver salts are dissolved in photography due to the formation of the thiosulfate complex Ag S2O3 2 3 and cyanide extraction for silver and gold works by the formation of the complex Ag CN 2 Silver cyanide forms the linear polymer Ag C N Ag C N silver thiocyanate has a similar structure but forms a zigzag instead because of the sp3 hybridized sulfur atom Chelating ligands are unable to form linear complexes and thus silver I complexes with them tend to form polymers a few exceptions exist such as the near tetrahedral diphosphine and diarsine complexes Ag L L 2 47 Organometallic Main article Organosilver chemistry Under standard conditions silver does not form simple carbonyls due to the weakness of the Ag C bond A few are known at very low temperatures around 6 15 K such as the green planar paramagnetic Ag CO 3 which dimerizes at 25 30 K probably by forming Ag Ag bonds Additionally the silver carbonyl Ag CO B OTeF5 4 is known Polymeric AgLX complexes with alkenes and alkynes are known but their bonds are thermodynamically weaker than even those of the platinum complexes though they are formed more readily than those of the analogous gold complexes they are also quite unsymmetrical showing the weak p bonding in group 11 Ag C s bonds may also be formed by silver I like copper I and gold I but the simple alkyls and aryls of silver I are even less stable than those of copper I which tend to explode under ambient conditions For example poor thermal stability is reflected in the relative decomposition temperatures of AgMe 50 C and CuMe 15 C as well as those of PhAg 74 C and PhCu 100 C 48 The C Ag bond is stabilized by perfluoroalkyl ligands for example in AgCF CF3 2 49 Alkenylsilver compounds are also more stable than their alkylsilver counterparts 50 Silver NHC complexes are easily prepared and are commonly used to prepare other NHC complexes by displacing labile ligands For example the reaction of the bis NHC silver I complex with bis acetonitrile palladium dichloride or chlorido dimethyl sulfide gold I 51 Intermetallic Different colors of silver copper gold alloys Silver forms alloys with most other elements on the periodic table The elements from groups 1 3 except for hydrogen lithium and beryllium are very miscible with silver in the condensed phase and form intermetallic compounds those from groups 4 9 are only poorly miscible the elements in groups 10 14 except boron and carbon have very complex Ag M phase diagrams and form the most commercially important alloys and the remaining elements on the periodic table have no consistency in their Ag M phase diagrams By far the most important such alloys are those with copper most silver used for coinage and jewellery is in reality a silver copper alloy and the eutectic mixture is used in vacuum brazing The two metals are completely miscible as liquids but not as solids their importance in industry comes from the fact that their properties tend to be suitable over a wide range of variation in silver and copper concentration although most useful alloys tend to be richer in silver than the eutectic mixture 71 9 silver and 28 1 copper by weight and 60 1 silver and 28 1 copper by atom 52 Most other binary alloys are of little use for example silver gold alloys are too soft and silver cadmium alloys too toxic Ternary alloys have much greater importance dental amalgams are usually silver tin mercury alloys silver copper gold alloys are very important in jewellery usually on the gold rich side and have a vast range of hardnesses and colours silver copper zinc alloys are useful as low melting brazing alloys and silver cadmium indium involving three adjacent elements on the periodic table is useful in nuclear reactors because of its high thermal neutron capture cross section good conduction of heat mechanical stability and resistance to corrosion in hot water 52 EtymologyThe word silver appears in Old English in various spellings such as seolfor and siolfor It is cognate with Old High German silabar Gothic silubr or Old Norse silfr all ultimately deriving from Proto Germanic silubra The Balto Slavic words for silver are rather similar to the Germanic ones e g Russian serebro serebro Polish srebro Lithuanian sidabras as is the Celtiberian form silabur They may have a common Indo European origin although their morphology rather suggest a non Indo European Wanderwort 53 54 Some scholars have thus proposed a Paleo Hispanic origin pointing to the Basque form zilharr as an evidence 55 The chemical symbol Ag is from the Latin word for silver argentum compare Ancient Greek ἄrgyros argyros from the Proto Indo European root h erǵ formerly reconstructed as arǵ meaning white or shining This was the usual Proto Indo European word for the metal whose reflexes are missing in Germanic and Balto Slavic 54 History Silver vase circa 2400 BC Silver was one of the seven metals of antiquity that were known to prehistoric humans and whose discovery is thus lost to history 56 In particular the three metals of group 11 copper silver and gold occur in the elemental form in nature and were probably used as the first primitive forms of money as opposed to simple bartering 57 However unlike copper silver did not lead to the growth of metallurgy on account of its low structural strength and was more often used ornamentally or as money 58 Since silver is more reactive than gold supplies of native silver were much more limited than those of gold 57 For example silver was more expensive than gold in Egypt until around the fifteenth century BC 59 the Egyptians are thought to have separated gold from silver by heating the metals with salt and then reducing the silver chloride produced to the metal 60 The situation changed with the discovery of cupellation a technique that allowed silver metal to be extracted from its ores While 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 9 and one of the earliest silver extraction centres in Europe was Sardinia in the early Chalcolithic period 61 these techniques did not spread widely until later when it spread throughout the region and beyond 59 The origins of silver production in India China and Japan were almost certainly equally ancient but are not well documented due to their great age 60 Silver mining and processing in Kutna Hora Bohemia 1490s When the Phoenicians first came to what is now Spain they obtained so much silver that they could not fit it all on their ships and as a result used silver to weight their anchors instead of lead 59 By the time of the Greek and Roman civilizations silver coins were a staple of the economy 57 the Greeks were already extracting silver from galena by the 7th century BC 59 and the rise of Athens was partly made possible by the nearby silver mines at Laurium from which they extracted about 30 tonnes a year from 600 to 300 BC 62 The stability of the Roman currency relied to a high degree on the supply of silver bullion mostly from Spain which Roman miners produced on a scale unparalleled before the discovery of the New World Reaching a peak production of 200 tonnes per year an estimated silver stock of 10 000 tonnes circulated in the Roman economy in the middle of the second century AD five to ten times larger than the combined amount of silver available to medieval Europe and the Abbasid Caliphate around AD 800 63 64 The Romans also recorded the extraction of silver in central and northern Europe in the same time period This production came to a nearly complete halt with the fall of the Roman Empire not to resume until the time of Charlemagne by then tens of thousands of tonnes of silver had already been extracted 60 Central Europe became the centre of silver production during the Middle Ages as the Mediterranean deposits exploited by the ancient civilisations had been exhausted Silver mines were opened in Bohemia Saxony Erzgebirge Alsace the Lahn region Siegerland Silesia Hungary Norway Steiermark Schwaz and the southern Black Forest Most of these ores were quite rich in silver and could simply be separated by hand from the remaining rock and then smelted some deposits of native silver were also encountered Many of these mines were soon exhausted but a few of them remained active until the Industrial Revolution before which the world production of silver was around a meagre 50 tonnes per year 60 In the Americas high temperature silver lead cupellation technology was developed by pre Inca civilizations as early as AD 60 120 silver deposits in India China Japan and pre Columbian America continued to be mined during this time 60 65 With the discovery of America and the plundering of silver by the Spanish conquistadors Central and South America became the dominant producers of silver until around the beginning of the 18th century particularly Peru Bolivia Chile and Argentina 60 the last of these countries later took its name from that of the metal that composed so much of its mineral wealth 62 The silver trade gave way to a global network of exchange As one historian put it silver went round the world and made the world go round 66 Much of this silver ended up in the hands of the Chinese A Portuguese merchant in 1621 noted that silver wanders throughout all the world before flocking to China where it remains as if at its natural center 67 Still much of it went to Spain allowing Spanish rulers to pursue military and political ambitions in both Europe and the Americas New World mines concluded several historians supported the Spanish empire 68 In the 19th century primary production of silver moved to North America particularly Canada Mexico and Nevada in the United States some secondary production from lead and zinc ores also took place in Europe and deposits in Siberia and the Russian Far East as well as in Australia were mined 60 Poland emerged as an important producer during the 1970s after the discovery of copper deposits that were rich in silver before the centre of production returned to the Americas the following decade Today Peru and Mexico are still among the primary silver producers but the distribution of silver production around the world is quite balanced and about one fifth of the silver supply comes from recycling instead of new production 60 Proto Elamite kneeling bull holding a spouted vessel 3100 2900 BC 16 3 6 3 10 8 cm Metropolitan Museum of Art New York City Ancient Egyptian figurine of Horus as falcon god with an Egyptian crown circa 500 BC silver and electrum height 26 9 cm Staatliche Sammlung fur Agyptische Kunst Munich Germany Ancient Greek tetradrachm 315 308 BC diameter 2 7 cm Metropolitan Museum of Art Ancient Greek gilded bowl 2nd 1st century BC height 7 6 cm dimeter 14 8 cm Metropolitan Museum of Art Roman plate 1st 2nd century AD height 0 1 cm diameter 12 7 cm Metropolitan Museum of Art Roman bust of Serapis 2nd century 15 6 9 5 cm Metropolitan Museum of Art Auricular basin with scenes from the story of Diana and Actaeon 1613 length 50 cm height 6 cm width 40 cm Rijksmuseum Amsterdam the Netherlands French Rococo tureen 1749 height 26 3 cm width 39 cm depth 24 cm Metropolitan Museum of Art French Rococo coffeepot 1757 height 29 5 cm Metropolitan Museum of Art French Neoclassical ewer 1784 1785 height 32 9 cm Metropolitan Museum of Art Neo Rococo coffeepot 1845 overall 32 23 8 15 4 cm Cleveland Museum of Art Cleveland Ohio USA French Art Nouveau dessert spoons circa 1890 Cooper Hewitt Smithsonian Design Museum New York City Art Nouveau jardiniere circa 1905 1910 height 22 cm width 47 cm depth 22 5 cm Cooper Hewitt Smithsonian Design Museum Hand mirror 1906 height 20 7 cm weight 88 g Rijksmuseum Amsterdam the Netherlands Mystery watch ca 1889 diameter 5 4 cm depth 1 8 cm Musee d Horlogerie of Le Locle Switzerland Symbolic role 16th century fresco painting of Judas being paid thirty pieces of silver for his betrayal of Jesus Silver plays a certain role in mythology and has found various usage as a metaphor and in folklore The Greek poet Hesiod s Works and Days lines 109 201 lists different ages of man named after metals like gold silver bronze and iron to account for successive ages of humanity 69 Ovid s Metamorphoses contains another retelling of the story containing an illustration of silver s metaphorical use of signifying the second best in a series better than bronze but worse than gold But when good Saturn banish d from above Was driv n to Hell the world was under Jove Succeeding times a silver age behold Excelling brass but more excell d by gold Ovid Metamorphoses Book I trans John Dryden In folklore silver was commonly thought to have mystic powers for example a bullet cast from silver is often supposed in such folklore the only weapon that is effective against a werewolf witch or other monsters 70 71 72 From this the idiom of a silver bullet developed into figuratively referring to any simple solution with very high effectiveness or almost miraculous results as in the widely discussed software engineering paper No Silver Bullet 73 Other powers attributed to silver include detection of poison and facilitation of passage into the mythical realm of fairies 72 Silver production has also inspired figurative language Clear references to cupellation occur throughout the Old Testament of the Bible such as in Jeremiah s rebuke to Judah The bellows are burned the lead is consumed of the fire the founder melteth in vain for the wicked are not plucked away Reprobate silver shall men call them because the Lord hath rejected them Jeremiah 6 19 20 Jeremiah was also aware of sheet silver exemplifying the malleability and ductility of the metal Silver spread into plates is brought from Tarshish and gold from Uphaz the work of the workman and of the hands of the founder blue and purple is their clothing they are all the work of cunning men Jeremiah 10 9 59 Silver also has more negative cultural meanings the idiom thirty pieces of silver referring to a reward for betrayal references the bribe Judas Iscariot is said in the New Testament to have taken from Jewish leaders in Jerusalem to turn Jesus of Nazareth over to soldiers of the high priest Caiaphas 74 Ethically silver also symbolizes greed and degradation of consciousness this is the negative aspect the perverting of its value 75 Occurrence and productionFurther information Silver mining World production of silver The abundance of silver in the Earth s crust is 0 08 parts per million almost exactly the same as that of mercury It mostly occurs in sulfide ores especially acanthite and argentite Ag2S Argentite deposits sometimes also contain native silver when they occur in reducing environments and when in contact with salt water they are converted to chlorargyrite including horn silver AgCl which is prevalent in Chile and New South Wales 76 Most other silver minerals are silver pnictides or chalcogenides they are generally lustrous semiconductors Most true silver deposits as opposed to argentiferous deposits of other metals came from Tertiary period vulcanism 77 The principal sources of silver are the ores of copper copper nickel lead and lead zinc obtained from Peru Bolivia Mexico China Australia Chile Poland and Serbia 9 Peru Bolivia and Mexico have been mining silver since 1546 and are still major world producers Top silver producing mines are Cannington Australia Fresnillo Mexico San Cristobal Bolivia Antamina Peru Rudna Poland and Penasquito Mexico 78 Top near term mine development projects through 2015 are Pascua Lama Chile Navidad Argentina Jaunicipio Mexico Malku Khota Bolivia 79 and Hackett River Canada 78 In Central Asia Tajikistan is known to have some of the largest silver deposits in the world 80 Silver is usually found in nature combined with other metals or in minerals that contain silver compounds generally in the form of sulfides such as galena lead sulfide or cerussite lead carbonate So the primary production of silver requires the smelting and then cupellation of argentiferous lead ores a historically important process 81 Lead melts at 327 C lead oxide at 888 C and silver melts at 960 C To separate the silver the alloy is melted again at the high temperature of 960 C to 1000 C in an oxidizing environment The lead oxidises to lead monoxide then known as litharge which captures the oxygen from the other metals present The liquid lead oxide is removed or absorbed by capillary action into the hearth linings 82 83 84 Ag s 2Pb s O2 g 2PbO absorbed Ag l Today silver metal is primarily produced instead as a secondary byproduct of electrolytic refining of copper lead and zinc and by application of the Parkes process on lead bullion from ore that also contains silver 85 In such processes silver follows the non ferrous metal in question through its concentration and smelting and is later purified out For example in copper production purified copper is electrolytically deposited on the cathode while the less reactive precious metals such as silver and gold collect under the anode as the so called anode slime This is then separated and purified of base metals by treatment with hot aerated dilute sulfuric acid and heating with lime or silica flux before the silver is purified to over 99 9 purity via electrolysis in nitrate solution 76 Commercial grade fine silver is at least 99 9 pure and purities greater than 99 999 are available In 2022 Mexico was the top producer of silver 6 300 tonnes or 24 2 of the world s total of 26 000 t followed by China 3 600 t and Peru 3 100 t 85 In marine environments Silver concentration is low in seawater pmol L Levels vary by depth and between water bodies Dissolved silver concentrations range from 0 3 pmol L in coastal surface waters to 22 8 pmol L in pelagic deep waters 86 Analyzing the presence and dynamics of silver in marine environments is difficult due to these particularly low concentrations and complex interactions in the environment 87 Although a rare trace metal concentrations are greatly impacted by fluvial aeolian atmospheric and upwelling inputs as well as anthropogenic inputs via discharge waste disposal and emissions from industrial companies 88 89 Other internal processes such as decomposition of organic matter may be a source of dissolved silver in deeper waters which feeds into some surface waters through upwelling and vertical mixing 89 In the Atlantic and Pacific silver concentrations are minimal at the surface but rise in deeper waters 90 Silver is taken up by plankton in the photic zone remobilized with depth and enriched in deep waters Silver is transported from the Atlantic to the other oceanic water masses 88 In North Pacific waters silver is remobilized at a slower rate and increasingly enriched compared to deep Atlantic waters Silver has increasing concentrations that follow the major oceanic conveyor belt that cycles water and nutrients from the North Atlantic to the South Atlantic to the North Pacific 91 There is not an extensive amount of data focused on how marine life is affected by silver despite the likely deleterious effects it could have on organisms through bioaccumulation association with particulate matters and sorption 86 Not until about 1984 did scientists begin to understand the chemical characteristics of silver and the potential toxicity In fact mercury is the only other trace metal that surpasses the toxic effects of silver however the full extent of silver toxicity is not expected in oceanic conditions because of its ability to transfer into nonreactive biological compounds 92 In one study the presence of excess ionic silver and silver nanoparticles caused bioaccumulation effects on zebrafish organs and altered the chemical pathways within their gills 93 In addition very early experimental studies demonstrated how the toxic effects of silver fluctuate with salinity and other parameters as well as between life stages and different species such as finfish molluscs and crustaceans 94 Another study found raised concentrations of silver in the muscles and liver of dolphins and whales indicating pollution of this metal within recent decades Silver is not an easy metal for an organism to eliminate and elevated concentrations can cause death 95 Monetary use A 2004 American Silver Eagle bullion coin minted in 999 fine silver The earliest known coins were minted in the kingdom of Lydia in Asia Minor around 600 BC 96 The coins of Lydia were made of electrum which is a naturally occurring alloy of gold and silver that was available within the territory of Lydia 96 Since that time silver standards in which the standard economic unit of account is a fixed weight of silver have been widespread throughout the world until the 20th century Notable silver coins through the centuries include the Greek drachma 97 the Roman denarius 98 the Islamic dirham 99 the karshapana from ancient India and rupee from the time of the Mughal Empire grouped with copper and gold coins to create a trimetallic standard 100 and the Spanish dollar 101 The ratio between the amount of silver used for coinage and that used for other purposes has fluctuated greatly over time for example in wartime more silver tends to have been used for coinage to finance the war 102 Today silver bullion has the ISO 4217 currency code XAG one of only four precious metals to have one the others being palladium platinum and gold 103 Silver coins are produced from cast rods or ingots rolled to the correct thickness heat treated and then used to cut blanks from These blanks are then milled and minted in a coining press modern coining presses can produce 8000 silver coins per hour 102 Price Price of silver 1968 2022 See also silver as an investment Silver prices are normally quoted in troy ounces One troy ounce is equal to 31 1034768 grams The London silver fix is published every working day at noon London time 104 This price is determined by several major international banks and is used by London bullion market members for trading that day Prices are most commonly shown as the United States dollar USD the Pound sterling GBP and the Euro EUR ApplicationsJewellery and silverware Embossed silver sarcophagus of Saint Stanislaus in the Wawel Cathedral was created in main centers of the 17th century European silversmithery Augsburg and Gdansk 105 17th century silverware The major use of silver besides coinage throughout most of history was in the manufacture of jewellery and other general use items and this continues to be a major use today Examples include table silver for cutlery for which silver is highly suited due to its antibacterial properties Western concert flutes are usually plated with or made out of sterling silver 106 in fact most silverware is only silver plated rather than made out of pure silver the silver is normally put in place by electroplating Silver plated glass as opposed to metal is used for mirrors vacuum flasks and Christmas tree decorations 107 Because pure silver is very soft most silver used for these purposes is alloyed with copper with finenesses of 925 1000 835 1000 and 800 1000 being common One drawback is the easy tarnishing of silver in the presence of hydrogen sulfide and its derivatives Including precious metals such as palladium platinum and gold gives resistance to tarnishing but is quite costly base metals like zinc cadmium silicon and germanium do not totally prevent corrosion and tend to affect the lustre and colour of the alloy Electrolytically refined pure silver plating is effective at increasing resistance to tarnishing The usual solutions for restoring the lustre of tarnished silver are dipping baths that reduce the silver sulfide surface to metallic silver and cleaning off the layer of tarnish with a paste the latter approach also has the welcome side effect of polishing the silver concurrently 106 Medicine Main article Medical uses of silver In medicine silver is incorporated into wound dressings and used as an antibiotic coating in medical devices Wound dressings containing silver sulfadiazine or silver nanomaterials are used to treat external infections Silver is also used in some medical applications such as urinary catheters where tentative evidence indicates it reduces catheter related urinary tract infections and in endotracheal breathing tubes where evidence suggests it reduces ventilator associated pneumonia 108 109 The silver ion is bioactive and in sufficient concentration readily kills bacteria in vitro Silver ions interfere with enzymes in the bacteria that transport nutrients form structures and synthesise cell walls these ions also bond with the bacteria s genetic material Silver and silver nanoparticles are used as an antimicrobial in a variety of industrial healthcare and domestic application for example infusing clothing with nanosilver particles thus allows them to stay odourless for longer 110 111 Bacteria can however develop resistance to the antimicrobial action of silver 112 Silver compounds are taken up by the body like mercury compounds but lack the toxicity of the latter Silver and its alloys are used in cranial surgery to replace bone and silver tin mercury amalgams are used in dentistry 107 Silver diammine fluoride the fluoride salt of a coordination complex with the formula Ag NH3 2 F is a topical medicament drug used to treat and prevent dental caries cavities and relieve dentinal hypersensitivity 113 Electronics Silver is very important in electronics for conductors and electrodes on account of its high electrical conductivity even when tarnished Bulk silver and silver foils were used to make vacuum tubes and continue to be used today in the manufacture of semiconductor devices circuits and their components For example silver is used in high quality connectors for RF VHF and higher frequencies particularly in tuned circuits such as cavity filters where conductors cannot be scaled by more than 6 Printed circuits and RFID antennas are made with silver paints 9 114 Powdered silver and its alloys are used in paste preparations for conductor layers and electrodes ceramic capacitors and other ceramic components 115 Brazing alloys Silver containing brazing alloys are used for brazing metallic materials mostly cobalt nickel and copper based alloys tool steels and precious metals The basic components are silver and copper with other elements selected according to the specific application desired examples include zinc tin cadmium palladium manganese and phosphorus Silver provides increased workability and corrosion resistance during usage 116 Chemical equipment Silver is useful in the manufacture of chemical equipment on account of its low chemical reactivity high thermal conductivity and being easily workable Silver crucibles alloyed with 0 15 nickel to avoid recrystallisation of the metal at red heat are used for carrying out alkaline fusion Copper and silver are also used when doing chemistry with fluorine Equipment made to work at high temperatures is often silver plated Silver and its alloys with gold are used as wire or ring seals for oxygen compressors and vacuum equipment 117 Catalysis Silver metal is a good catalyst for oxidation reactions in fact it is somewhat too good for most purposes as finely divided silver tends to result in complete oxidation of organic substances to carbon dioxide and water and hence coarser grained silver tends to be used instead For instance 15 silver supported on a Al2O3 or silicates is a catalyst for the oxidation of ethylene to ethylene oxide at 230 270 C Dehydrogenation of methanol to formaldehyde is conducted at 600 720 C over silver gauze or crystals as the catalyst as is dehydrogenation of isopropanol to acetone In the gas phase glycol yields glyoxal and ethanol yields acetaldehyde while organic amines are dehydrated to nitriles 117 Photography The photosensitivity of the silver halides allowed for their use in traditional photography although digital photography which does not use silver is now dominant The photosensitive emulsion used in black and white photography is a suspension of silver halide crystals in gelatin possibly mixed in with some noble metal compounds for improved photosensitivity developing and tuning clarify Colour photography requires the addition of special dye components and sensitisers so that the initial black and white silver image couples with a different dye component The original silver images are bleached off and the silver is then recovered and recycled Silver nitrate is the starting material in all cases 118 The use of silver nitrate and silver halides in photography has rapidly declined with the advent of digital technology From the peak global demand for photographic silver in 1999 267 000 000 troy ounces or 8 304 6 tonnes the market contracted almost 70 by 2013 119 Nanoparticles Main article Silver nanoparticle Nanosilver particles between 10 and 100 nanometres in size are used in many applications They are used in conductive inks for printed electronics and have a much lower melting point than larger silver particles of micrometre size They are also used medicinally in antibacterials and antifungals in much the same way as larger silver particles 111 In addition according to the European Union Observatory for Nanomaterials EUON silver nanoparticles are used both in pigments as well as cosmetics 120 121 Miscellanea A tray of South Asian sweets with some pieces covered with shiny silver vark Pure silver metal is used as a food colouring It has the E174 designation and is approved in the European Union 122 Traditional Indian and Pakistani dishes sometimes include decorative silver foil known as vark 123 and in various other cultures silver dragee are used to decorate cakes cookies and other dessert items 124 Photochromic lenses include silver halides so that ultraviolet light in natural daylight liberates metallic silver darkening the lenses The silver halides are reformed in lower light intensities Colourless silver chloride films are used in radiation detectors Zeolite sieves incorporating Ag ions are used to desalinate seawater during rescues using silver ions to precipitate chloride as silver chloride Silver is also used for its antibacterial properties for water sanitisation but the application of this is limited by limits on silver consumption Colloidal silver is similarly used to disinfect closed swimming pools while it has the advantage of not giving off a smell like hypochlorite treatments do colloidal silver is not effective enough for more contaminated open swimming pools Small silver iodide crystals are used in cloud seeding to cause rain 111 The Texas Legislature designated silver the official precious metal of Texas in 2007 125 PrecautionsSilver HazardsGHS labelling Pictograms Signal word WarningHazard statements H410Precautionary statements P273 P391 P501 126 NFPA 704 fire diamond 000 Silver compounds have low toxicity compared to those of most other heavy metals as they are poorly absorbed by the human body when ingested and that which does get absorbed is rapidly converted to insoluble silver compounds or complexed by metallothionein However silver fluoride and silver nitrate are caustic and can cause tissue damage resulting in gastroenteritis diarrhoea falling blood pressure cramps paralysis and respiratory arrest Animals repeatedly dosed with silver salts have been observed to experience anaemia slowed growth necrosis of the liver and fatty degeneration of the liver and kidneys rats implanted with silver foil or injected with colloidal silver have been observed to develop localised tumours Parenterally admistered colloidal silver causes acute silver poisoning 127 Some waterborne species are particularly sensitive to silver salts and those of the other precious metals in most situations however silver does not pose serious environmental hazards 127 In large doses silver and compounds containing it can be absorbed into the circulatory system and become deposited in various body tissues leading to argyria which results in a blue grayish pigmentation of the skin eyes and mucous membranes Argyria is rare and so far as is known does not otherwise harm a person s health though it is disfiguring and usually permanent Mild forms of argyria are sometimes mistaken for cyanosis a blue tint on skin caused by lack of oxygen 127 9 Metallic silver like copper is an antibacterial agent which was known to the ancients and first scientifically investigated and named the oligodynamic effect by Carl Nageli Silver ions damage the metabolism of bacteria even at such low concentrations as 0 01 0 1 milligrams per litre metallic silver has a similar effect due to the formation of silver oxide This effect is lost in the presence of sulfur due to the extreme insolubility of silver sulfide 127 Some silver compounds are very explosive such as the nitrogen compounds silver azide silver amide and silver fulminate as well as silver acetylide silver oxalate and silver II oxide They can explode on heating force drying illumination or sometimes spontaneously To avoid the formation of such compounds ammonia and acetylene should be kept away from silver equipment Salts of silver with strongly oxidising acids such as silver chlorate and silver nitrate can explode on contact with materials that can be readily oxidised such as organic compounds sulfur and soot 127 See alsoSilver coin Silver medal Free silver List of countries by silver production List of silver compounds Silver as an investment Silverpoint drawingReferences Standard Atomic Weights Silver CIAAW 1985 Ag 0 has been observed in carbonyl complexes in low temperature matrices see McIntosh D Ozin G A 1976 Synthesis using metal vapors Silver carbonyls Matrix infrared ultraviolet visible and electron spin resonance spectra structures and bonding of silver tricarbonyl silver dicarbonyl silver monocarbonyl and disilver hexacarbonyl J Am Chem Soc 98 11 3167 75 doi 10 1021 ja00427a018 Lide D R ed 2005 Magnetic susceptibility of the elements and inorganic compounds CRC Handbook of Chemistry and Physics PDF 86th ed Boca Raton FL CRC Press ISBN 0 8493 0486 5 Weast Robert 1984 CRC Handbook of Chemistry and Physics Boca Raton Florida Chemical Rubber Company Publishing pp E110 ISBN 0 8493 0464 4 Poole Charles P Jr 11 March 2004 Encyclopedic Dictionary of Condensed Matter Physics Academic Press ISBN 978 0 08 054523 3 Bullion vs Numismatic Coins Difference between Bullion and Numismatic Coins providentmetals com Retrieved 17 December 2017 World has 5 times more gold than silver Latest News amp Updates at Daily News amp Analysis dna 3 March 2009 Retrieved 17 December 2017 Masuda Hideki 2016 Combined Transmission Electron Microscopy In situ Observation of the Formation Process and Measurement of Physical Properties for Single Atomic Sized Metallic Wires In Janecek Milos Kral Robert eds Modern Electron Microscopy in Physical and Life Sciences InTech doi 10 5772 62288 ISBN 978 953 51 2252 4 S2CID 58893669 a b c d e f g Hammond C R 2004 The Elements in Handbook of Chemistry and Physics 81st ed CRC press ISBN 978 0 8493 0485 9 a b c d Greenwood and Earnshaw p 1177 a b Greenwood and Earnshaw p 1178 George L Trigg Edmund H Immergut 1992 Encyclopedia of applied physics Vol 4 Combustion to Diamagnetism VCH Publishers pp 267 72 ISBN 978 3 527 28126 8 Retrieved 2 May 2011 Austin Alex 2007 The Craft of Silversmithing Techniques Projects Inspiration Sterling Publishing Company Inc p 43 ISBN 978 1 60059 131 0 Edwards H W Petersen R P 1936 Reflectivity of evaporated silver films Physical Review 50 9 871 Bibcode 1936PhRv 50 871E doi 10 1103 PhysRev 50 871 Silver vs Aluminum Gemini 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2006 The Oxford Introduction to Proto Indo European and the Proto Indo European World Oxford University Press pp 241 242 ISBN 978 0 19 928791 8 Boutkan Dirk Kossmann Maarten 2001 On the Etymology of Silver NOWELE North Western European Language Evolution 38 1 3 15 doi 10 1075 nowele 38 01bou Weeks p 4 a b c Greenwood and Earnshaw pp 1173 74 Readon Arthur C 2011 Metallurgy for the Non Metallurgist ASM International pp 73 84 ISBN 978 1 61503 821 3 a b c d e Weeks pp 14 19 a b c d e f g h Brumby et al pp 16 19 Melis Maria Grazia 2014 Silver in Neolithic and Eneolithic Sardinia In Meller H Risch R Pernicka E eds Metalle der Macht Fruhes Gold und Silber Metals of power Early gold and silver Landesamt fur Denkmalpflege und Archaologie Sachsen Anhalt ISBN 978 3944507057 a b Emsley John 2011 Nature s building blocks an A Z guide to the elements Oxford University Press pp 492 98 ISBN 978 0 19 960563 7 Patterson C C 1972 Silver Stocks and Losses in Ancient and Medieval Times The Economic History 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373 83 doi 10 3109 1040841X 2012 713323 PMID 22928774 S2CID 27527124 a b c Brumby et al pp 83 84 Panacek Ales Kvitek Libor Smekalova Monika Vecerova Renata Kolar Milan Roderova Magdalena Dycka Filip Sebela Marek Prucek Robert Tomanec Ondrej Zboril Radek January 2018 Bacterial resistance to silver nanoparticles and how to overcome it Nature Nanotechnology 13 1 65 71 Bibcode 2018NatNa 13 65P doi 10 1038 s41565 017 0013 y PMID 29203912 S2CID 26783560 Rosenblatt A Stamford T C M Niederman R 2009 Silver diamine fluoride a caries silver fluoride bullet Journal of Dental Research 88 2 116 25 doi 10 1177 0022034508329406 PMID 19278981 S2CID 30730306 Nikitin Pavel V Lam Sander amp Rao K V S 2005 Low Cost Silver Ink RFID Tag Antennas PDF 2005 IEEE Antennas and Propagation Society International Symposium Vol 2B p 353 doi 10 1109 APS 2005 1552015 ISBN 978 0 7803 8883 3 S2CID 695256 Archived from the original PDF on 21 March 2016 Brumby et al pp 71 78 Brumby et al pp 78 81 a b Brumby et al pp 81 82 Brumby et al p 82 A Big Source of Silver Bullion Demand Has Disappeared BullionVault Retrieved 20 July 2014 Pigments ECHA euon echa europa eu permanent dead link Catalogue of cosmetic ingredients ECHA euon echa europa eu permanent dead link Martinez Abad A Ocio M J Lagaron J M Sanchez G 2013 Evaluation of silver infused polylactide films for inactivation of Salmonella and feline calicivirus in vitro and on fresh cut vegetables International Journal of Food Microbiology 162 1 89 94 doi 10 1016 j ijfoodmicro 2012 12 024 PMID 23376782 Sarvate Sarita 4 April 2005 Silver Coating India Currents Archived from the original on 14 February 2009 Retrieved 5 July 2009 Meisler Andy 18 December 2005 A Tempest on a Tea Cart Los Angeles Times Hatch Rosie Ed 2022 Texas Almanac 2022 2023 Austin Texas Texas State Historical Association p 23 ISBN 9781625110664 Msds 373249 Sigma Aldrich a b c d e Brumby et al pp 88 91Cited sourcesBrumby Andreas et al 2008 Silver Silver Compounds and Silver Alloys Ullmann s Encyclopedia of Industrial Chemistry Weinheim Wiley VCH doi 10 1002 14356007 a24 107 pub2 Greenwood Norman N Earnshaw Alan 1997 Chemistry of the Elements 2nd ed Butterworth Heinemann ISBN 978 0 08 037941 8 Weeks Mary Elvira Leichester Henry M 1968 Discovery of the Elements Easton PA Journal of Chemical Education ISBN 978 0 7661 3872 8 LCCN 68 15217 External linksSilver at Wikipedia s sister projects Definitions from Wiktionary Media from Commons Quotations from Wikiquote Listen to this article 12 minutes source source This audio file was created from a revision of this article dated 1 September 2005 2005 09 01 and does not reflect subsequent edits Audio help More spoken articles Silver at The Periodic Table of Videos University of Nottingham Society of American Silversmiths The Silver Institute A silver industry website A collection of silver items Samples of silver Transport Fate and Effects of Silver in the Environment CDC NIOSH Pocket Guide to Chemical Hazards Silver Picture in the 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