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← silver →
[] 4d10 5s1
Electrons per shell
2, 8, 18, 18, 1
Physical properties
(at )
0; (961.78 °C, 0;°F)
;K (;°C, ;°F)
(near r.t.)
10.49 g/cm3
when liquid (at m.p.)
9.320 g/cm3
11.28 
254 kJ/mol
25.350 J/(mol·K)
P (Pa)
100 k
at T (K)
Atomic properties
-2, -1, 1, 2, 3 (an
Pauling scale: 1.93
1st: 731.0 kJ/mol
2nd: ;kJ/mol
3rd: ;kJ/mol
empirical: 144 
145±5 pm
172 pm
Miscellanea
thin rod
;m/s (at r.t.)
18.9 um/(m·K) (at 25 °C)
429 W/(m·K)
174 mm2/s (at 300 K)
15.87 nΩ·m (at 20 °C)
-19.5·10-6 cm3/mol (296 K)
83 GPa
30 GPa
100 GPa
251 MPa
206–250 MPa
41.2 d
8.28 d
418 y
7.45 d
Silver is a
with symbol Ag (from the
argentum, derived from the
?ργ??: "shiny" or "white") and
47. A soft, white, lustrous , it exhibits the highest , , and
of any . The metal is found in the Earth's crust in the pure, free elemental form ("native silver"), as an
and other metals, and in minerals such as
and . Most silver is produced as a byproduct of , gold, , and
Silver has long been valued as a . Silver metal is used in many
, sometimes : while it is more abundant than gold, it is much less abundant as a . Its purity is typically
a 94%-pure alloy is described as "0.940 fine". As one of the seven , silver has had an enduring role in most human cultures.
Other than in
medium ( and ), silver is used in , , , ornaments, high-value tableware and utensils (hence the term ), in
and , in specialized mirrors, window coatings, in
of chemical reactions, as a colorant in
and in specialised confectionery. Its compounds are used in
film. Dilute solutions of
and other silver compounds are used as
and microbiocides (), added to
and wound-dressings, , and other .
Silver is extremely ductile, and can be drawn into a monoatomic wire.
Silver is similar in its physical and chemical properties to its two vertical neighbours in
and . Its 47 electrons are arranged in the
[Kr]4d105s1, similarly to copper ([Ar]3d104s1) and gold ([Xe]4f145d106s1); group 11 is one of the few groups in the
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 the singular properties of metallic silver.
Silver is an extremely soft,
, though it is slightly less malleable than gold. Silver crystallizes in a
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 a
character and are relatively weak. This observation explains the low
and high ductility of
of silver.
Silver has a brilliant white metallic luster that can take a high , and which is so characteristic that the name of the metal itself has become a . Unlike copper and gold, the energy required to excite an electron from the filled d band to the s-p conduction band in silver is large enough (around 385 kJ/mol) that it no longer corresponds to absorption in the visible region of the spectrum, hence silver is not a coloured metal. Protected silver has greater optical
at all wavelengths longer than ~450 nm. At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm.
Very high electrical and thermal conductivity is 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
of silver is the greatest of all metals, greater even than copper, but it is not widely used for this property because of the higher cost. An exception is in , particularly at
and higher frequencies where silver plating improves electrical conductivity because those
rather than through the interior. During
in the US, 13540 tons of silver were used in
for enriching , mainly because of the wartime shortage of copper. Pure silver has the highest
of any metal, although the conductivity of
are even higher. Silver also has the lowest
of any metal.
Silver readily forms
with copper and gold, as well as . 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
(electron concentration 1.5),
(1.615), and
phases (1.75).
Naturally occurring silver is composed of two stable , 107Ag and 109Ag, with 107Ag being slightly more abundant (51.839% ). This almost equal abundance is rare in the periodic table. The
is 107.8682(2) ; this value is very important because of the importance of silver compounds, particularly halides, in . Both isotopes of silver are produced in stars via the
(slow neutron capture), as well as in supernovas via the
(rapid neutron capture).
Twenty-eight
have been characterized, the most stable being 105Ag with a
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 , 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
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
from 92.950 u (93Ag) to 129.950 u (130Ag); the primary
before the most abundant stable isotope, 107Ag, is
and the primary mode after is . The primary
before 107Ag are
(element 46) isotopes, and the primary products after are
(element 48) isotopes.
The palladium
107Pd decays by beta emission to 107Ag with a half-life of 6.5 million years.
are the only objects with a high-enough palladium-to-silver ratio to yield measurable variations in 107Ag abundance.
107Ag was first discovered in the
meteorite in 1978. The discoverers suggest the coalescence and differentiation of iron-cored small
may have occurred 10 million years after a
event. 107Pd–107Ag correlations observed in bodies that have clearly been melted since the
must reflect the presence of unstable nuclides in the early solar system.
Oxidation states and stereochemistries of silver
Coordination
Stereochemistry
Representative
[Ag(CN)2]-
Trigonal planar
AgI(PEt2Ar)2
Tetrahedral
[Ag(diars)2]+
Octahedral
AgF, AgCl, AgBr
Square planar
[Ag(py)4]2+
Square planar
Octahedral
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
(E0(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 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
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 large enough for this factor to have a much smaller effect, and furthermore the second ionisation energy of silver is greater than that for copper. Hence, Ag+ is the stable species in aqueous solution and solids, with Ag2+ being much less stable as it oxidizes water.
Despite the above formulations, most silver compounds have significant
character due to the small size and high first ionization energy (730.8 kJ/mol) of silver. Furthermore, silver's Pauling
of 1.93 is higher than that of
(1.87), and its
of 125.6 kJ/mol is much higher than that of
(72.8 kJ/mol) and not much less than that of
(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 , forming linear complexes showing very low
like 2, and forming an amphoteric oxide as well as
like the . Unlike the preceding transition metals, the +1 oxidation state of silver is stable even in the absence of .
Silver does not react with air, even at red heat, and thus was considered by
along with gold. Its reactivity is intermediate between that of copper (which forms
when heated in air to red heat) and gold. Like copper, silver reacts wit in their presence, silver tarnishes in air to form the black
(copper forms the green
instead, while gold does not react). Unlike copper, silver will not react with the halogens, with the exception of the notoriously reactive
gas, with which it forms the . While silver is not attacked by non-oxidizing acids, the metal dissolves readily in hot concentrated , as well as dilute or concentrated . In the presence of air, and especially in the presence of , silver dissolves readily in aqueous solutions of .
The three main forms of deterioration in historical silver artifacts are tarnishing, formation of
due to long-term immersion in salt water, as well as reaction with
ions or oxygen. Fresh silver chloride is pale yellow, becoming purplish
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
7), and in the presence of
(KBr). These compounds are used in photography to
silver images, converting them to silver bromide that can either be fixed with
or redeveloped to
the original image. Silver forms
complexes () that are soluble in water in the presence of an excess of cyanide ions. Silver cyanide solutions are used in
of silver.
The common
of silver are (in order of commonness): +1 (t for example, , AgNO3); +2 ( for example, , AgF2); and even very rarely +3 ( for example, potassium tetrafluoroargentate(III), KAgF4). The +1 state is by far the most common, followed by the easily reducible +2 state. The +3 state requires very strong oxidising agents to attain, such as
or , and some silver(III) compounds react with atmospheric moisture and attack glass. Indeed, silver(III) fluoride is usually obtained by reacting silver or silver monofluoride with the strongest known oxidizing agent, .
Silver(I) sulfide
Silver and gold have rather low
for oxygen, lower than copper, and it is therefore expected that silver oxides are thermally quite unstable. Soluble silver(I) salts precipitate dark-brown , Ag2O, upon the addition of alkali. (The hydroxide AgOH exi 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. This and other silver(I) compounds may be oxidized by the strong oxidizing agent
to black AgO, a mixed
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.
, 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
with silver metal or aqueous Ag+ ions. Many non-stoichiome in particular, AgTe~3 is a low-temperature .
The three common silver halide precipitates: from left to right, , , and .
The only known dihalide of silver is , 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 .
In stark contrast to this, all four silver(I) halides are known. The , , and
have the sodium chloride structure, but the
has three known stable forms at di that at room temperature is the cubic
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 color changes from the white chloride to the yellow iodide as the energy required for
(X-Ag+ → XAg) decreases. The fluoride is anomalous, as the fluoride ion is so small that it has a considerable
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
methods. All four are
(though the monofluoride is so only to
light), especially the bromide and iodide which photodecompose to silver metal, and thus were used in traditional photography. The reaction involved is:
X- + hν → 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
or an impurity site, so that the electron's energy is lowered enough that it is "trapped".
Crystals of silver nitrate
White , 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. 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 , e.g. for
and oxidations. Ag+ binds
reversibly, and silver nitrate has been used to separate mixtures of alkenes by selective absorption. The resulting
can be decomposed with
to release the free alkene.
Yellow , Ag2CO3 can be easily prepared by reacting aqueous solutions of
with a deficiency of silver nitrate. Its principal use is for the production of silver powder for use in microelectronics. It is reduced with , producing silver free of alkali metals:
Ag2CO3 + CH2O → 2 Ag + 2 CO2 + H2
Silver carbonate is also used as a
in organic synthesis such as the . In the , silver carbonate on
acts as an
from . It is also employed to convert
bromides into .
, AgCNO, a powerful, touch-sensitive
used in , is made by reaction of silver metal with nitric acid in the presence of . Other dangerously explosive silver compounds are , AgN3, formed by reaction of
with , and , Ag2C2, formed when silver reacts with
solution. 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.
3 (s) → 3 N
2 (g) + 2 Ag (s)
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 . The yellow diamagnetic [AgF4]- 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 Ag2+, produced by oxidation of Ag+ by ozone, is a very strong oxidising agent, even in acidic solutions: it is stabilized in
due to complex formation. Peroxodisulfate oxidation is generally necessary to give the more stable complexes with heterocyclic , 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.
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
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
has a similar structure, but forms a zigzag instead because of the sp3- sulfur atom.
are unable to form linear complexes and thus silver(I) complexes with them t a few exceptions exist, such as the near-tetrahedral
complexes [Ag(L–L)2]+.
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
are known, but their bonds are thermodynamically weaker than even those of the
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).
The C–Ag bond is stabilized by
ligands, for example in AgCF(CF3)2. Alkenylsilver compounds are also more stable than their alkylsilver counterparts. Silver- 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
Different colors of silver–copper–gold alloys
Silver forms
with most other elements on the periodic table. The elements from groups 1–3, except for , , and , are very miscible with silver in the condensed phase and form int those from groups 4–9 are
the elements in groups 10–14 (except
and ) have very complex Ag–M phase diagrams and form the most commercia 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
is used in vacuum . The two metals are completely miscible as liqui 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– alloys too toxic. Ternary alloys have much greater importance: dental
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– (involving three adjacent elements on the periodic table) is useful in
because of its high thermal neutron capture , good conduction of heat, mechanical stability, and resistance to corrosion in hot water.
The word "silver" appears in
in various spellings, such as seolfor and siolfor. A similar form is seen throughout the
silabar and silbir). The chemical symbol Ag is from the
word for "silver", argentum (compare
?ργυρο?, árgyros), from the
root *h?er?- (formerly reconstructed as *ar?-), meaning "white" or "shining": this was the usual Proto-Indo-European word for the metal, whose reflexes are missing in Germanic and . The Balto-Slavic words for silver are quite similar to the Germanic ones (e.g.
серебро [serebro],
sidabras) and they may have a common origin, although this is uncertain: some scholars have suggested the
sarpu "refined silver" as this origin, related to the word sarapu "to refine or smelt".
Silver plate from the 4th century
Silver was one of the seven
that were known to prehistoric humans and whose discovery is thus lost to history. In particular, the three metals of group 11, copper, silver, and gold, occur in the
in nature and were probably used as the first primitive forms of
as opposed to simple bartering. However, unlike copper, silver did not lead to the growth of
on account of its low structural strength, and 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
produced to the metal.
The situation changed with the discovery of , a technique that allowed silver metal to be extracted from its ores. While
heaps found in
and on the islands of the
indicate that silver was being separated from
as early as the , and one of the earliest silver extraction centres in Europe was
in early the , these techniques did not spread widely until later, when it spread throughout the region and beyond. The origins of silver production in , , and
were almost certainly equally ancient, but are not well-documented due to their great age.
Silver mining and processing in , Bohemia, 1490s
first came to what is now , 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 the Greek and Roman civilizations, silver coins were a staple of the economy: the Greeks were already extracting silver from
by the 7th century BC, and the rise of
was partly made possible by the nearby silver mines at , from which they extracted about 30 tonnes a year from 600 to 300 BC. The stability of the
relied to a high degree on the supply of silver bullion, mostly from Spain, which
produced on a scale unparalleled before the . Reaching a peak production of 200 tonnes per year, an estimated silver stock of 10000 tonnes circulated in the
in the middle of the second century AD, five to ten times larger than the combined amount of silver available to
around AD 800. 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 : by then, tens of thousands of tonnes of silver had already been extracted.
Central Europe became the centre of silver production during the , as the Mediterranean deposits exploited by the ancient civilisations had been exhausted. Silver mines were opened in , , , , the
region, , , , , , , and the southern . Most of these ores were quite rich in silver and could simply be separated by hand from the remaining r some deposits of native silver were also encountered. Many of these mines were soon exhausted, but a few of them remained active until the , before which the world production of silver was around a meagre 50 tonnes per year. In the Americas, high temperature silver-lead
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 the dominant producers of silver until around the beginning of the 18th century, particularly , , , and : the last of these countries later took its name from that of the metal that composed so much of its mineral wealth. In the 19th century, primary production of silver moved to North America, particularly , , and
in the : some secondary production from lead and zinc ores also took place in Europe, and deposits in
as well as in
were mined.
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.
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 's
(lines 109–201) lists different
named after metals like gold, silver, bronze and iron to account for successive ages of humanity. 's
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 , banish'd from above,
Was driv'n to Hell, the world was under .
Succeeding times a silver age behold,
Excelling brass, but more excell'd by gold.
— Ovid, , Book I, trans.
In folklore, silver was commonly thought to have mystic powers: for example, a
cast from silver is often supposed in such folklore the only weapon that is effective against a , , or other . From this the idiom of a
developed into figuratively referring to any simple solution with very high effectiveness or almost miraculous results, as in the widely discussed
Silver production has also inspired figurative language. Clear references to cupellation occur throughout the
of the , such as in 's rebuke to Judah: "The bellows are burned, the lead is
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)
Silver also has more negative cultural meanings: the idiom , referring to a reward for betrayal, references the bribe
is said in the
to have taken from Jewish leaders in
over to soldiers of the high priest Caiaphas. Ethically, silver also symbolizes greed and degradat this is the negative aspect, the perverting of its value.
Acanthite sample from the Chispas Mine in , ; scale at bottom of image as one inch with a rule at one centimetre
The abundance of silver in the Earth's crust is 0.08 , almost exactly the same as that of . It mostly occurs in
ores, especially
and , Ag2S. Argentite deposits sometimes also contain
silver when they occur in reducing environments, and when in contact with salt water they are converted to
(including ), AgCl, which is prevalent in
and . Most other silver mine they are generally lustrous semiconductors. Most true silver deposits, as opposed to argentiferous deposits of other metals, came from
vulcanism.
The principal sources of silver are the ores of copper, copper-nickel, lead, and lead-zinc obtained from , , , , , ,
and . Peru, Bolivia and Mexico have been mining silver since 1546, and are still major world producers. Top silver-producing mines are
(Australia),
(Bolivia),
(Poland), and
(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 ,
is known to have some of the largest silver deposits in the world.
Silver is usually found in nature combined with other metals, or in minerals that contain silver compounds, generally in the form of
(lead sulfide) or
(lead carbonate). So the primary production of silver requires the smelting and then
of argentiferous lead ores, a historically important process. 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 ;°C in an oxidizing environment. The lead oxidises to , then known as , which captures the oxygen from the other metals present. The liquid lead oxide is removed or absorbed by
into the hearth linings.
Ag(s) + 2Pb(s) + O
2(g) → 2PbO(absorbed) + Ag(l)
Today, silver metal is primarily produced instead as a secondary byproduct of
refining of copper, lead, and zinc, and by application of the
on lead bullion from ore that also contains silver. 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
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
acid and heating with lime or silica flux, before the silver is purified to over 99.9% purity via electrolysis in
Commercial-grade fine silver is at least 99.9% pure, and purities greater than 99.999% are available. In 2014, Mexico was the top producer of silver (5,000
or 18.7% of the world's total of 26,800 t), followed by China (4,060 t) and Peru (3,780 t).
1,000 oz silver bar
The earliest known coins of the Western world were minted in the kingdom of
around 600 BC. The coins of Lydia were made of , which is a naturally occurring
of gold and silver, that was available within the territory of Lydia. Since that time, , in which the standard economic
is a fixed weight of silver, have been widespread throughout the world until the 20th century. Notable
through the centuries include the , the Roman , the Islamic , the
from the time of the
(grouped with copper and gold coins to create a trimetallic standard), and the .
The ratio between the amount of silver used for coinage and that used for other purposes has fluctuat for example, in wartime, more silver tends to have been used for coinage to finance the war.
Today, silver bullion has the
currency code XAG, one of only four
to have one (the others being , , and gold). Silver coins are produced from cast rods or ingots, rolled to the correct thickness, heat-treated, and then used to cut
from. These blanks are then milled and minte modern coining presses can produce 8000 silver coins per hour.
Silver prices are normally quoted in Troy ounces which equals 31.1034 grams. Prices most commonly shown in US dollars, a London silver price occurs daily where major international banks conduct and publish a fixing at noon London time. Unlike the gold A.m. and P.m. fix there is only one silver fixing per day.
As of January 2018, silver is valued at around $554 per kilogram, or about $17 per ounce.
Silver toilet set of
The major use of silver besides coinage throughout most of history was in the manufacture of
and other general-use items, and this continues to be a major use today. Examples include
for cutlery, for which silver is highly suited due to its antibacterial properties.
are usually plated
in fact, most silverware is only silver-plated rather than mad the silver is normally put in place by . Silver-plated glass (as opposed to metal) is used for mirrors, , and Christmas tree decorations.
Because pure silver is very soft, most silver used for these purposes is alloyed with copper, with finenesses of 925/00, and 800/1000 being common. One drawback is the easy tarnishing of silver in the presence of
and its derivatives. Including precious metals such as palladium, platinum, and gold gives resistance to tarnishing
like , , , and
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
the latter approach also has the welcome side effect of polishing the silver concurrently. A simple chemical approach to removal of the sulfide tarnish is to bring silver items into contact with aluminium foil whilst immersed in water containing a conducting salt, such as sodium chloride.[]
In medicine, silver is incorporated into wound dressings and used as an antibiotic coating in medical devices. Wound dressings containing
are used to treat external infections. Silver is also used in some medical applications, such as
(where tentative evidence indicates it reduces catheter-related ) and in
(where evidence suggests it reduces ventilator-associated ). The silver
and in sufficient
readily kills
. They interfere with enzymes in the bacteria that transport nutrients, form structures, synthesise cell walls, and bond with the bacteria's genetic material. Microbes cannot develop resistance to silver as they can to antibiotics, and hence 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. Silver compounds are taken up by the body like
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. , the fluoride salt of a
with the formula [Ag(NH3)2]F, is a topical
(drug) used to treat and prevent
(cavities) and relieve dentinal hypersensitivity.
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 , , and higher frequencies, particularly in tuned circuits such as
where conductors cannot be scaled by more than 6%.
antennas are made with silver paints, Powdered silver and its alloys are used in paste preparations for conductor layers and electrodes, ceramic capacitors, and other ceramic components.
Silver-containing
alloys are used for brazing metallic materials, mostly , , 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, , and . Silver provides increased workability and corrosion resistance during usage.
Silver is useful in the manufacture of chemical equipment on account of its low chemical reactivity, high thermal conductivity, and being easily workable. Silver
(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 . 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.
Silver metal is a good cat in fact it is somewhat too good for most purposes, as finely divided silver tends to result in complete oxidation of organic substances to
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
at 230–270 °C. Dehydrogenation of
is conducted at 600–720 °C over silver gauze or crystals as the catalyst, as is dehydrogenation of
to . In the gas phase,
yields , while organic
are dehydrated to .
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. 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.
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 0,000
or 8304.6 ) the market contracted almost 70% by 2013.
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.
A tray of , with some pieces covered with shiny silver vark
Pure silver metal is used as a food colouring. It has the
designation and is approved in the . Traditional Pakistani and Indian dishes sometimes include decorative silver foil known as , and in various other cultures, silver
are used to decorate cakes, cookies, and other dessert items.
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.
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.
is similarly used to disinfect c while it has the advantage of not giving off a smell like
treatments do, colloidal silver is not effective enough for more contaminated open swimming pools. Small
crystals are used in
to cause rain.
Silver compounds have low toxicity compared to those of most other , as they are poorly absorbed by the human body when digested, and that which does get absorbed is rapidly converted to insoluble silver compounds or complexed by . However, silver fluoride and silver nitrate are caustic and can cause tissue damage, resulting in , , falling , cramps, paralysis, and . Animals repeatedly dosed with silver salts have been observed to experience , slowed growth, necrosis of the liver, and fatty degeneration of t rats implanted with silver foil or injected with
have been observed to develop localised tumours.
admistered colloidal silver causes acute silver poisoning. Some waterborne species are particularly sensitive to silver salts and those of the o in most situations, however, silver does not pose serious environmental hazards.
In large doses, silver and compounds containing it can be absorbed into the
and become deposited in various body tissues, leading to , which results in a blue-grayish pigmentation of the skin, eyes, and . 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 .
Metallic silver, like copper, is an antibacterial agent, which was known to the ancients and first scientifically investigated and named the
by . Silver ions damage the metabolism of bacteria even at such low concentrations as 0.01–0.1  metallic silver has a similar effect due to the formation of silver oxide. This effect is lost in the presence of
due to the extreme insolubility of silver sulfide.
Some silver compounds are very explosive, such as the nitrogen compounds silver azide, silver , and silver fulminate, as well as , , and silver(II) oxide. They can explode on heating, force, drying, illumination, or sometimes spontaneously. To avoid the formation of such compounds, ammonia and
should be kept away from silver equipment. Salts of silver with strongly oxidising acids such as
and silver nitrate can explode on contact with materials that can be readily oxidised, such as organic compounds, sulfur and soot.
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