Pan American Silver Corporation is a mining company based in Canada with operations in Latin America. The company has mines and other projects in Mexico, Peru , Bolivia , and Argentina .
93-509: It is one of the world's biggest silver producers; in 2017 the company extracted 25 million ounces of Silver , 160,000 ounces of Gold , 55,300 ounces of Zinc , 21,500 tonnes of Lead , and 13,400 tonnes of Copper . Pan American Silver was founded in April 1994 by Ross Beaty. Beaty had previously founded and run Equinox Resources, which he eventually sold to an American mining company. It listed on NASDAQ in 1995 and acquired its Quiruvilca mine in
186-486: A bullet cast from silver is often supposed in such folklore the only weapon that is effective against a werewolf , witch , or other monsters . 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 ." Other powers attributed to silver include detection of poison and facilitation of passage into
279-496: A covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant, white, metallic luster that can take a high polish , and which is so characteristic that the name of the metal itself has become a color name . Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm. At wavelengths shorter than 450 nm, silver's reflectivity
372-400: A closed electrical circuit , one charged particle does not need to travel from the component producing the current (the current source ) to those consuming it (the loads ). Instead, the charged particle simply needs to nudge its neighbor a finite amount, who will nudge its neighbor, and on and on until a particle is nudged into the consumer, thus powering it. Essentially what is occurring is
465-450: 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 . Silver is similar in its physical and chemical properties to its two vertical neighbours in group 11 of
558-454: A conductor of uniform cross section, therefore, can be computed as where ℓ {\displaystyle \ell } is the length of the conductor, measured in metres [m], A is the cross-section area of the conductor measured in square metres [m ], σ ( sigma ) is the electrical conductivity measured in siemens per meter (S·m ), and ρ ( rho ) is the electrical resistivity (also called specific electrical resistance ) of
651-418: A few hundred amperes. Aside from the geometry of the wire, temperature also has a significant effect on the efficacy of conductors. Temperature affects conductors in two main ways, the first is that materials may expand under the application of heat. The amount that the material will expand is governed by the thermal expansion coefficient specific to the material. Such an expansion (or contraction) will change
744-411: A given material, the resistance is inversely proportional to the cross-sectional area. For example, a thick copper wire has lower resistance than an otherwise-identical thin copper wire. Also, for a given material, the resistance is proportional to the length; for example, a long copper wire has higher resistance than an otherwise-identical short copper wire. The resistance R and conductance G of
837-457: A long chain of momentum transfer between mobile charge carriers ; the Drude model of conduction describes this process more rigorously. This momentum transfer model makes metal an ideal choice for a conductor; metals, characteristically, possess a delocalized sea of electrons which gives the electrons enough mobility to collide and thus affect a momentum transfer. As discussed above, electrons are
930-575: A non-Indo-European Wanderwort . Some scholars have thus proposed a Paleo-Hispanic origin, pointing to the Basque form zilharr as an evidence. 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
1023-417: A reducing atmosphere, then oxygen-free high conductivity copper (CW008A or ASTM designation C10100) may be used. Because of its ease of connection by soldering or clamping, copper is still the most common choice for most light-gauge wires. Silver is 6% more conductive than copper, but due to cost it is not practical in most cases. However, it is used in specialized equipment, such as satellites , and as
SECTION 10
#17328729350841116-598: 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. Ethically, silver also symbolizes greed and degradation of consciousness; this is the negative aspect, the perverting of its value. The abundance of silver in the Earth's crust is 0.08 parts per million , almost exactly
1209-612: 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. The Romans also recorded the extraction of silver in central and northern Europe in
1302-482: A share. Tahoe's largest asset was its shuttered Escobal Silver Mine in Guatemala, which faced widespread protests and had significant human rights violations where security guards shot locals, leading to a high profile court case. Markets reacted to the news, with Pan American's share price falling 12% whereas Tahoe's rose 50%. As of November 2018, Pan American has six operating mines: Silver Silver
1395-575: A thin plating to mitigate skin effect losses at high frequencies. Famously, 14,700 short tons (13,300 t) of silver on loan from the United States Treasury were used in the making of the calutron magnets during World War II due to wartime shortages of copper. Aluminum wire is the most common metal in electric power transmission and distribution . Although only 61% of the conductivity of copper by cross-sectional area, its lower density makes it twice as conductive by mass. As aluminum
1488-556: 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
1581-465: Is the difluoride , AgF 2 , 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 . 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
1674-470: Is Ag 3 O which behaves as a metallic conductor. Silver(I) sulfide , Ag 2 S, 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 . The only known dihalide of silver
1767-551: Is a chemical element ; it has symbol Ag (from Latin argentum 'silver', derived from Proto-Indo-European *h₂erǵ ' shiny, white ' ) and atomic number 47. A soft, white, lustrous transition metal , it exhibits the highest electrical conductivity , thermal conductivity , and reflectivity of any metal . Silver 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
1860-438: 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 ( E (Ag /Ag) = +0.799 V). 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
1953-549: 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). 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 as well as Zintl phases like
SECTION 20
#17328729350842046-428: Is inferior to that of aluminium and drops to zero near 310 nm. 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. The thermal conductivity of silver is among the highest of all materials, although
2139-516: Is known to have some of the largest silver deposits in the world. Electrical conductor In physics and electrical engineering , a conductor is an object or type of material that allows the flow of charge ( electric current ) in one or more directions. Materials made of metal are common electrical conductors. The flow of negatively charged electrons generates electric current, positively charged holes , and positive or negative ions in some cases. In order for current to flow within
2232-413: Is much less stable, fuming in moist air and reacting with glass. 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 Ag , produced by oxidation of Ag by ozone, is a very strong oxidising agent, even in acidic solutions: it
2325-404: Is not exact: It assumes the current density is totally uniform in the conductor, which is not always true in practical situation. However, this formula still provides a good approximation for long thin conductors such as wires. Another situation this formula is not exact for is with alternating current (AC), because the skin effect inhibits current flow near the center of the conductor. Then,
2418-410: 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". White silver nitrate , AgNO 3 , 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
2511-424: 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. Silver metal is attacked by strong oxidizers such as potassium permanganate ( KMnO 4 ) and potassium dichromate ( K 2 Cr 2 O 7 ), and in
2604-404: Is passed through it. Liquids made of compounds with only covalent bonds cannot conduct electricity. Certain organic ionic liquids , by contrast, can conduct an electric current. While pure water is not an electrical conductor, even a small portion of ionic impurities, such as salt , can rapidly transform it into a conductor. Wires are measured by their cross sectional area. In many countries,
2697-402: Is produced as a byproduct of copper , gold, lead , and zinc refining . Silver has long been valued as a precious metal . Silver metal is used in many bullion coins , sometimes alongside gold : while it is more abundant than gold, it is much less abundant as a native metal . Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of
2790-415: Is rare in the periodic table. The atomic weight is 107.8682(2) u ; this value is very important because of the importance of silver compounds, particularly halides, in gravimetric analysis . 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). Twenty-eight radioisotopes have been characterized,
2883-531: 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). The C–Ag bond is stabilized by perfluoroalkyl ligands, for example in AgCF(CF 3 ) 2 . Alkenylsilver compounds are also more stable than their alkylsilver counterparts. Silver- NHC complexes are easily prepared, and are commonly used to prepare other NHC complexes by displacing labile ligands. For example,
Pan American Silver - Misplaced Pages Continue
2976-650: Is roughly one-third the cost of copper by weight, the economic advantages are considerable when large conductors are required. The disadvantages of aluminum wiring lie in its mechanical and chemical properties. It readily forms an insulating oxide, making connections heat up. Its larger coefficient of thermal expansion than the brass materials used for connectors causes connections to loosen. Aluminum can also "creep", slowly deforming under load, which also loosens connections. These effects can be mitigated with suitably designed connectors and extra care in installation, but they have made aluminum building wiring unpopular past
3069-472: 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 ] and [Ag(bipy) 2 ] : these are stable provided the counterion cannot reduce the silver back to the +1 oxidation state. [AgF 4 ] is also known in its violet barium salt, as are some silver(II) complexes with N - or O -donor ligands such as pyridine carboxylates. By far
3162-413: Is the cubic zinc blende structure. They can all be obtained by the direct reaction of their respective elements. As the halogen group is descended, the silver halide gains more and more covalent character, solubility decreases, and the colour changes from the white chloride to the yellow iodide as the energy required for ligand-metal charge transfer (X Ag → XAg) decreases. The fluoride is anomalous, as
3255-574: Is the international standard to which all other electrical conductors are compared; the International Annealed Copper Standard conductivity is 58 MS/m , although ultra-pure copper can slightly exceed 101% IACS. The main grade of copper used for electrical applications, such as building wire, motor windings, cables and busbars , is electrolytic-tough pitch (ETP) copper (CW004A or ASTM designation C100140). If high conductivity copper must be welded or brazed or used in
3348-726: 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). 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
3441-404: Is usually insulated with PVC insulation that is only rated to operate to about 60 °C, therefore, the current in such wires must be limited so that it never heats the copper conductor above 60 °C, causing a risk of fire . Other, more expensive insulation such as Teflon or fiberglass may allow operation at much higher temperatures. If an electric field is applied to a material, and
3534-482: Is usually obtained by reacting silver or silver monofluoride with the strongest known oxidizing agent, krypton difluoride . 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 , Ag 2 O, upon the addition of alkali. (The hydroxide AgOH exists only in solution; otherwise it spontaneously decomposes to
3627-528: The Institute for Policy Studies found that Pan-American Silver was involved in several environmental conflicts in Latin America and that these conflicts "demonstrate a lack of respect for communities defending their territories from mining." In November 2018, Pan American announced it would acquire Tahoe Resources , a Nevada-based mining firm with mines in Latin America and Canada, for $ 1.1 billion or about $ 5
3720-843: 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 . 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 , AgN 3 , formed by reaction of silver nitrate with sodium azide , and silver acetylide , Ag 2 C 2 , formed when silver reacts with acetylene gas in ammonia solution. In its most characteristic reaction, silver azide decomposes explosively, releasing nitrogen gas: given
3813-532: 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
Pan American Silver - Misplaced Pages Continue
3906-484: The geometrical cross-section is different from the effective cross-section in which current actually flows, so the resistance is higher than expected. Similarly, if two conductors are near each other carrying AC current, their resistances increase due to the proximity effect . At commercial power frequency , these effects are significant for large conductors carrying large currents, such as busbars in an electrical substation , or large power cables carrying more than
3999-646: The mythical realm of fairies . 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
4092-433: The periodic table : copper , and gold . Its 47 electrons are arranged in the configuration [Kr]4d 5s , similarly to copper ([Ar]3d 4s ) and gold ([Xe]4f 5d 6s ); group 11 is one of the few groups in the d-block which has a completely consistent set of electron configurations. This distinctive electron configuration, with a single electron in the highest occupied s subshell over a filled d subshell, accounts for many of
4185-435: 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
4278-526: The post-transition metals . Unlike the preceding transition metals, the +1 oxidation state of silver is stable even in the absence of π-acceptor ligands . 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
4371-440: The service drop . Organic compounds such as octane, which has 8 carbon atoms and 18 hydrogen atoms, cannot conduct electricity. Oils are hydrocarbons, since carbon has the property of tetracovalency and forms covalent bonds with other elements such as hydrogen, since it does not lose or gain electrons, thus does not form ions. Covalent bonds are simply the sharing of electrons. Hence, there is no separation of ions when electricity
4464-702: 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. Poland emerged as an important producer during the 1970s after the discovery of copper deposits that were rich in silver, before
4557-568: The Greek and Roman civilizations, silver coins were a staple of the economy: the Greeks were already extracting silver from galena by the 7th century BC, 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. 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
4650-553: The ancient alchemists, who believed that silver was associated with the Moon. It is often used for gravimetric analysis, exploiting the insolubility of the heavier silver halides which it is a common precursor to. 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
4743-637: The black silver sulfide (copper forms the green sulfate instead, while gold does not react). 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 . 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
SECTION 50
#17328729350844836-707: 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. 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. Ovid 's Metamorphoses contains another retelling of
4929-462: The conductor is made from (as described above) and the conductor's size. For a given material, conductors with a larger cross-sectional area have less resistance than conductors with a smaller cross-sectional area. For bare conductors, the ultimate limit is the point at which power lost to resistance causes the conductor to melt. Aside from fuses , most conductors in the real world are operated far below this limit, however. For example, household wiring
5022-434: The dominant producers of silver until around the beginning of the 18th century, particularly Peru , Bolivia , Chile , and Argentina : the last of these countries later took its name from that of the metal that composed so much of its mineral wealth. 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." Much of this silver ended up in
5115-411: 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
5208-526: The exceptions are the nitrate, perchlorate, and fluoride. The tetracoordinate tetrahedral aqueous ion [Ag(H 2 O) 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(NH 3 ) 2 ] ; silver salts are dissolved in photography due to the formation of the thiosulfate complex [Ag(S 2 O 3 ) 2 ] ; and cyanide extraction for silver (and gold) works by
5301-534: The fluoride ion is so small that it has a considerable solvation energy and hence is highly water-soluble and forms di- and tetrahydrates. The other three silver halides are highly insoluble in aqueous solutions and are very commonly used in gravimetric analytical methods. 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 . The reaction involved is: The process
5394-523: 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 sp - 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 ] . Under standard conditions, silver does not form simple carbonyls, due to
5487-412: The free alkene. Yellow silver carbonate , Ag 2 CO 3 can be easily prepared by reacting aqueous solutions of sodium carbonate with a deficiency of silver nitrate. 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: Silver carbonate is also used as a reagent in organic synthesis such as
5580-426: The geometry of the conductor and therefore its characteristic resistance. However, this effect is generally small, on the order of 10 . An increase in temperature will also increase the number of phonons generated within the material. A phonon is essentially a lattice vibration, or rather a small, harmonic kinetic movement of the atoms of the material. Much like the shaking of a pinball machine, phonons serve to disrupt
5673-567: 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. The word silver appears in Old English in various spellings, such as seolfor and siolfor . It
SECTION 60
#17328729350845766-504: 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." 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." In
5859-443: The material, measured in ohm-metres (Ω·m). The resistivity and conductivity are proportionality constants, and therefore depend only on the material the wire is made of, not the geometry of the wire. Resistivity and conductivity are reciprocals : ρ = 1 / σ {\displaystyle \rho =1/\sigma } . Resistivity is a measure of the material's ability to oppose electric current. This formula
5952-606: The metal. 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 , and one of the earliest silver extraction centres in Europe was Sardinia in the early Chalcolithic period , these techniques did not spread widely until later, when it spread throughout
6045-434: 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:
6138-546: The most stable being Ag with a half-life of 41.29 days, Ag with a half-life of 7.45 days, and Ag with a half-life of 3.13 hours. Silver has numerous nuclear isomers , the most stable being Ag ( t 1/2 = 418 years), Ag ( t 1/2 = 249.79 days) and Ag ( t 1/2 = 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. Isotopes of silver range in relative atomic mass from 92.950 u ( Ag) to 129.950 u ( Ag);
6231-573: The only objects with a high-enough palladium-to-silver ratio to yield measurable variations in Ag abundance. Radiogenic Ag was first discovered in the Santa Clara meteorite in 1978. Pd– Ag 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. Silver is a rather unreactive metal. This
6324-625: The ores of copper, copper-nickel, lead, and lead-zinc obtained from Peru , Bolivia , Mexico , China , Australia , Chile , Poland and Serbia . 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). Top near-term mine development projects through 2015 are Pascua Lama (Chile), Navidad (Argentina), Jaunicipio (Mexico), Malku Khota (Bolivia), and Hackett River (Canada). In Central Asia , Tajikistan
6417-423: The oxide.) Silver(I) oxide is very easily reduced to metallic silver, and decomposes to silver and oxygen above 160 °C. 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 Ag Ag O 2 . Some other mixed oxides with silver in non-integral oxidation states, namely Ag 2 O 3 and Ag 3 O 4 , are also known, as
6510-427: The path of electrons, causing them to scatter. This electron scattering will decrease the number of electron collisions and therefore will decrease the total amount of current transferred. Conduction materials include metals , electrolytes , superconductors , semiconductors , plasmas and some nonmetallic conductors such as graphite and conductive polymers . Copper has a high conductivity . Annealed copper
6603-577: The photosensitivity of silver salts, this behaviour may be induced by shining a light on its crystals. 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(IO 5 OH) 2 ] and tellurate [Ag{TeO 4 (OH) 2 } 2 ] complexes may be prepared by oxidising silver(I) with alkaline peroxodisulfate . The yellow diamagnetic [AgF 4 ]
6696-961: 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. The common oxidation states of silver are (in order of commonness): +1 (the most stable state; for example, silver nitrate , AgNO 3 ); +2 (highly oxidising; for example, silver(II) fluoride , AgF 2 ); and even very rarely +3 (extreme oxidising; for example, potassium tetrafluoroargentate(III), KAgF 4 ). 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. Indeed, silver(III) fluoride
6789-406: The primary decay mode before the most abundant stable isotope, Ag, is electron capture and the primary mode after is beta decay . The primary decay products before Ag are palladium (element 46) isotopes, and the primary products after are cadmium (element 48) isotopes. The palladium isotope Pd decays by beta emission to Ag with a half-life of 6.5 million years. Iron meteorites are
6882-425: The primary mover in metals; however, other devices such as the cationic electrolyte (s) of a battery , or the mobile protons of the proton conductor of a fuel cell rely on positive charge carriers. Insulators are non-conducting materials with few mobile charges that support only insignificant electric currents. The resistance of a given conductor depends on the material it is made of, and on its dimensions. For
6975-419: The reaction of the bis(NHC)silver(I) complex with bis(acetonitrile)palladium dichloride or chlorido(dimethyl sulfide)gold(I) : 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;
7068-502: The region and beyond. 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. 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. By the time of
7161-697: The same as that of mercury . It mostly occurs in sulfide ores, especially acanthite and argentite , Ag 2 S. 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 . 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. The principal sources of silver are
7254-669: 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. 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 , Alsace ,
7347-702: The same year. In 1998, it acquired the La Colorada Mine in Mexico, and in 2000 it acquired the Huaron mine in Peru. In 2012, Pan American acquired Minefinders Corporation for C$ 1.5 billion; Minefinders principal asset was the Dolores Mine in Mexico. In 2018, it temporarily curtailed operations at its Dolores mine in Mexico, due to violence in the area. In 2020, research carried out by EJAtlas , MiningWatch Canada , Earthworks and
7440-440: 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
7533-429: The singular properties of metallic silver. 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. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking
7626-408: The size is expressed in square millimetres. In North America, conductors are measured by American wire gauge for smaller ones, and circular mils for larger ones. The ampacity of a conductor, that is, the amount of current it can carry, is related to its electrical resistance: a lower-resistance conductor can carry a larger value of current. The resistance, in turn, is determined by the material
7719-422: 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. Unlike copper , for which the larger hydration energy of Cu as compared to Cu is the reason why the former is the more stable in aqueous solution and solids despite lacking
7812-445: 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 Ag being much less stable as it oxidizes water. Most silver compounds have significant covalent character due to the small size and high first ionization energy (730.8 kJ/mol) of silver. Furthermore, silver's Pauling electronegativity of 1.93
7905-411: 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. In folklore, silver was commonly thought to have mystic powers: for example,
7998-463: 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). Naturally occurring silver is composed of two stable isotopes , Ag and Ag, with Ag being slightly more abundant (51.839% natural abundance ). This almost equal abundance
8091-477: 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. 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
8184-540: The thermal conductivity of carbon (in the diamond allotrope ) and superfluid helium-4 are higher. 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. 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
8277-458: 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(OTeF 5 ) 4 ] is known. Polymeric AgLX complexes with alkenes and alkynes are known, but their bonds are thermodynamically weaker than even those of
8370-495: The world production of silver was around a meagre 50 tonnes per year. 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. With the discovery of America and the plundering of silver by the Spanish conquistadors, Central and South America became
8463-413: 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) Silver also has more negative cultural meanings: the idiom thirty pieces of silver , referring to
8556-501: Was more often used ornamentally or as money. Since silver is more reactive than gold, supplies of native silver were much more limited than those of gold. For example, silver was more expensive than gold in Egypt until around the fifteenth century BC: the Egyptians are thought to have separated gold from silver by heating the metals with salt, and then reducing the silver chloride produced to
8649-457: Was the usual Proto-Indo-European word for the metal, whose reflexes are missing in Germanic and Balto-Slavic. Silver was known in prehistoric times: 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. Unlike copper, silver did not lead to the growth of metallurgy , on account of its low structural strength; it
#83916