Silver chemical element - main properties, deposits and methods of obtaining the metal

Silver

(
Ag
from Latin Argentum) is an element of group 11 (according to the outdated classification - a secondary subgroup of the first group), the fifth period of D. I. Mendeleev’s periodic table of chemical elements, with atomic number 47.

Simple substance silver

- malleable, ductile noble metal of silver-white color. The crystal lattice is face-centered cubic. Melting point - 962 °C, density - 10.5 g/cm³.

Story

Silver has been known to mankind since ancient times. This is due to the fact that at one time silver, like gold, was often found in its native form - it did not have to be smelted from ores. This predetermined the rather significant role of silver in the cultural traditions of various peoples. One of the oldest centers for the extraction and processing of silver was prehistoric Sardinia, where it was known since the early Eneolithic.

In Assyria and Babylon, silver was considered a sacred metal and was a symbol of the Moon. In the Middle Ages, silver and its compounds were very popular among alchemists. Since the middle of the 13th century, silver has become a traditional material for making tableware. In addition, silver is still used to this day for minting commemorative coins (the withdrawal of the last silver coins from circulation in the 1960s and 1970s approximately coincided with the crisis of the Bretton Woods monetary system).

origin of name

Slavic names of metal - Russian. silver, Polish srebro, Bulgarian silver, ancient glory silver - goes back to the Proto-Slavic *sеrebro

, which has correspondences in the Baltic (Lit. sidabras, Old Prussian
sirablan
) and Germanic (Gothic silubr, German Silber, English silver) languages.
Further etymology outside the German-Balto-Slavic circle of languages ​​is unclear, suggesting either a derivation from the same base as Anatolian subau-ro
“brilliant”, or an early borrowing from the languages ​​of the Middle East: cf. Akkadian sarpu "refined silver", from Akkad. sarapu “to purify, to melt,” or from the pre-Indo-European languages ​​of ancient Europe: cf. Basque. zilar.

The Greek name for silver is ἄργυρος, árgyros

comes from the Indo-European root
*H₂erǵó-, *H₂erǵí-
, meaning “white, shining.”
argentum,
comes from the same root .

origin of name

If we talk about the name in more detail, then everything is not as simple as mentioned above. Not only in the Proto-Slavic dialect there was a word similar to the modern “silver”. The discovery of specialists showed that similar words exist in the Anatolian group of languages, in languages ​​common in the Middle East, as well as in pre-Indo-European languages ​​of European countries.

It is very difficult, if not impossible, to establish the degree to which a word belongs to a particular culture. There is also a Greek word for silver, árgyros, from which comes the Latin argentum, adopted by the international community as the main name in the international system and periodic table.

Being in nature

The average silver content in the earth's crust (according to Vinogradov) is 70 mg/t. Its maximum concentrations are found in clayey shales, where they reach 1 g/t. Silver is characterized by a relatively low energy index of ions, which causes an insignificant manifestation of isomorphism of this element and its relatively difficult inclusion in the lattice of other minerals. Only a constant isomorphism of silver and lead ions is observed. Silver ions are included in the lattice of native gold, the amount of which sometimes reaches almost 50% by weight in electrum. In small quantities, the silver ion is included in the lattice of copper sulfides and sulfosalts, as well as in the composition of tellurides developed in some polymetallic and especially in gold-sulfide and gold-quartz deposits.

A certain part of noble and non-ferrous metals occurs in nature in native form. The facts of finding not just large, but huge nuggets of silver are known and documented. For example, in 1477, a silver nugget weighing 20 tons was discovered at the St. George mine (Schneeberg deposit in the Ore Mountains, 40-45 km from the city of Freiberg). A block of silver measuring 1 × 1 × 2.2 m was dragged out of the mine workings, had a festive dinner on it, and then split it and weighed it. In Denmark, in the Copenhagen Museum, there is a nugget weighing 254 kg, discovered in 1666 at the Norwegian Kongsberg mine. Large nuggets were also discovered on other continents. Currently, one of the native silver plates mined at the Cobalt mine in Canada, weighing 612 kg, is stored in the Canadian Parliament building. Another plate, found at the same deposit and called “silver pavement” for its size, was about 30 m long and contained 20 tons of silver. However, with all the impressiveness of the finds ever discovered, it should be noted that silver is chemically more active than gold, and for this reason is less common in nature in its native form. For the same reason, the solubility of silver is higher and its concentration in seawater is an order of magnitude greater than that of gold (about 0.04 μg/l and 0.004 μg/l, respectively).

Silver ore, Primorye

More than 50 natural silver minerals are known, of which only 15–20 are of industrial importance, including:

• native silver;
• electrum (gold-silver);
• kustelite (silver-gold);
• argentite (silver-sulfur);
• proustite (silver-arsenic-sulfur);
• bromargerite (silver-bromine);
• kerargyrite (silver-chlorine);
• pyrargyrite (silver-antimony-sulfur);
• stephanite (silver-antimony-sulfur);
• polybasite (silver-copper-antimony-sulfur);
• freibergite (copper-sulfur-silver);
• argentoyarosite (silver-iron-sulfur);
• dyscrazite (silver-antimony);
• aguilarite (silver-selenium-sulfur)

Like other noble metals, silver has two types of manifestations:

• actual silver deposits, where it accounts for more than 50% of the cost of all useful components;
• complex silver-containing deposits (in which silver is included in the ores of non-ferrous, alloying and precious metals as an associated component).

Silver deposits themselves play a fairly significant role in global silver production, but it should be noted that the main proven reserves of silver (75%) come from complex deposits.

The silver content in ores of non-ferrous metals is 10-100 g/t, in gold-silver ores 200-1000 g/t, and in ores of silver deposits 900-2000 g/t, sometimes tens of kilograms per ton.

Silver is also found in caustobolites: peat, oil, coal, bituminous shale.

Place of Birth

Silver production by country (2011)
Significant silver deposits are located in the territories of the following countries:

• Armenia,
• Germany,
• Spain,
• Peru,
• Chile,
• Mexico,
• China,
• Canada,
• USA,
• Australia,
• Poland,
• Russia,
• Kazakhstan,
• Romania,
• Sweden,
• Czech Republic,
• Slovakia,
• Austria,
• Hungary,
• Norway.

There are also silver deposits in Cyprus and Sardinia.

The richest deposits

Silver deposits are almost evenly distributed across all continents, but undisputed leaders in its production have emerged in the world. I have compiled lists of the richest and most famous deposits to date.

In the world

The most promising deposits with annual silver production are as follows:

• Cannington (Australia), 1430 tons;
• Fresnillo (Mexico), 982 tons;
• Dukat (Russia), 375 t;
• Uchuchacua (Peru), 305 tons;
• Greens Creek (USA), 302 tons;
• Arcata (Peru), 247 tons;
• Rochester (USA), 176 tons;
• Imiter (Morocco), 153 tons;
• Juaron (Peru), 126 tons;
• Lunnoe (Russia), 115 t.

In Russia

Russia is one of the world leaders in silver mining today. The richest deposits with the best characteristics in terms of the amount of precious metal per ton of ore:

• Dukat (Magadan), 640 g/t;
• Lunnoe (Magadan), 404 g/t;
• Khakanjinskoye (Khabarovsk), 344 g/t;
• Goltsovoye (Magadan), 1213 g/t;
• Forecast (Yakutia), 876 g/t;
• Podolskoe (Bashkortostan), 28 g/t;
• Gorevskoye (Krasnoyarsk), 56 g/t;
• Ozernoye (Buryatia), 35 g/t;
• Uzelginskoye (Chelyabinsk), 30 g/t;
• Gayskoye (Orenburg), 11 g/t.

Physical properties

Silver coin
Pure silver is a fairly heavy (lighter than lead, but heavier than copper, density - 10.5 g/cm³), unusually ductile silver-white metal (light reflection coefficient is close to 100%). Thin silver foil appears violet in transmitted light. Over time, the metal tarnishes, reacting with traces of hydrogen sulfide in the air and forming a coating of sulfide, whose thin film then gives the metal its characteristic pinkish color. It has the highest thermal conductivity among metals. At room temperature it has the highest electrical conductivity among all known metals (electrical resistivity 1.59⋅10−8 Ohm m at a temperature of 20 °C). A relatively refractory metal, melting point 962 °C.

Advantages and disadvantages

Due to its exceptional electrical and thermal conductivity characteristics, silver is widely used in the manufacture of electrical appliances. However, it is too expensive a metal to be used as needed.

High reflectivity provides a magnificent shine to jewelry made from it, but sterling silver is too soft and jewelry quickly loses its beauty. Therefore, alloying metals have to be added to the composition.

Alloys and samples

Precious metal is most often used in the form of alloys. What the ligature consists of largely determines its properties. So, copper gives the metal hardness. Tin, zinc and cadmium make the alloy suitable for solders by greatly reducing the melting point. Nickel enhances strength, while lead and aluminum, on the contrary, make the substance brittle.

Samples are used to indicate the purity content of the alloy. The product is marked in accordance with the metric system, for example, 800 - 80% silver and 20% alloy.

In jewelry alloys, copper is used as an alloying additive. As the sample decreases, the hardness of the metal increases, but the resistance to oxidation decreases and a noticeable yellowness appears. The most common varieties are:

• 800 is the lowest grade and most durable, has a clear yellowish tint, and is amazingly suitable for making fountain pens, cutlery and other actively used items.
• 830 - rarely used in the jewelry industry due to rapid oxidation and the yellowish tint of the metal.
• 875 – also has high strength and is used in the manufacture of inexpensive jewelry.
• 916 – not currently used to create jewelry. During the Soviet era, jugs, sugar bowls, gravy boats and other utensils were made from such an alloy.
• 925 is the so-called sterling silver, durable and malleable. Previously served as a material for minting banknotes. The most common alloy.
• 960 – used for expensive jewelry with filigree design elements. This alloy is an excellent material for fine work, but is too soft and easily deformed.
• 999 is a chemically pure metal, used to create investment instruments: bank bars, commemorative, anniversary and other coins.

Sample correspondence table

To determine the fineness of an alloy, many countries use the carat system, in which a fineness of 24 carats corresponds to pure metal. Conversion tables are used to convert carat to metric values.

Chemical properties

Silver, being a noble metal, has a relatively low reactivity; it does not dissolve in hydrochloric and dilute sulfuric acids. However, in an oxidizing environment (in nitric acid, hot concentrated sulfuric acid, and also in hydrochloric acid in the presence of free oxygen), silver dissolves:

Ag + 2HNO3(conc) = AgNO3 + NO2↑ + H2O

It also dissolves in ferric chloride, which is used for etching:

Ag + FeCl3 = AgCl + FeCl2

Silver also dissolves easily in mercury, forming an amalgam (a liquid alloy of mercury and silver).

Silver is not oxidized by oxygen even at high temperatures, but in the form of thin films it can be oxidized by oxygen plasma or ozone when irradiated with ultraviolet light. In humid air in the presence of even the slightest traces of divalent sulfur (hydrogen sulfide, thiosulfates, rubber), a deposit of poorly soluble silver sulfide is formed, causing the darkening of silver items:

4Ag + 2H2S + O2 = 2Ag2S + 2H2O

In the absence of oxygen:

2Ag + H2S = Ag2S + H2↑

Free halogens easily oxidize silver to halides:

2Ag + I2 = 2AgI

However, in the light this reaction is reversed, and the silver halides (except fluoride) gradually decompose. The principle of black and white photography is based on this phenomenon.

When heated with sulfur, silver gives sulfide:

2Ag + S = Ag2S

The most stable oxidation state of silver in compounds is +1. In the presence of ammonia, silver (I) compounds give the complex [Ag(NH3)2]+, which is easily soluble in water. Silver also forms complexes with cyanides and thiosulfates. Complexation is used to dissolve poorly soluble silver compounds and to extract silver from ores. Silver exhibits higher oxidation states (+2, +3) only in combination with oxygen (AgO, Ag2O3) and fluorine (AgF2, AgF3); such compounds are much less stable than silver (I) compounds.

Silver(I) salts, with rare exceptions (nitrate, perchlorate, fluoride), are insoluble in water, which is often used to determine halogen ions (chlorine, bromine, iodine) in aqueous solution.

Where can you buy or sell

In jewelry stores you can purchase jewelry of various sizes to suit every taste and budget. Merchants provide a wide selection of silver items of various grades and types.

The easiest way to sell such a product is to buy it at a pawn shop, or use all kinds of online trading platforms.

How much does 1 gram cost today?

The price for 1 gram of silver continuously changes depending on supply and demand on the world market based on the results of daily trading. All traders are guided by it, be it a bank or a pawnshop. You can monitor changes in metal prices using an interactive table.

Price per scrap

The cost of silver scrap directly depends on the purity of the metal and the degree of demand for the alloy at the moment. I will leave here a table with prices for scrap for ease of calculations.

Application

Silver bars

• Since it has the highest electrical conductivity, thermal conductivity and resistance to oxidation by oxygen under normal conditions, it is used for contacts of electrical products (for example, relay contacts, lamellas), as well as multilayer ceramic capacitors.
• The solders contain: copper-silver solders PSr-72, PSr-45 and others, used for soldering a variety of critical connections, including dissimilar metals; solders with a high silver content are used in jewelry, and with a medium content - in a variety of equipment, from high-current switches to liquid rocket engines, sometimes also as an additive to lead in the amount of 3% (PSr-3), it replaces tin solder.
• Composed of alloys: for the manufacture of cathodes of galvanic cells.
• It is used as a precious metal in jewelry (usually in an alloy with copper, sometimes with nickel and other metals).
• It is used in the minting of coins (circulating coins until the early 1970s, now only commemorative coins), as well as awards - orders and medals.
• Silver halides and silver nitrate are used in photography because they have high photosensitivity.
• Silver iodide is used to change the weather (“dispersal of clouds”).
• Due to the highest electrical conductivity and oxidation resistance, it is used: in electrical engineering and electronics as a coating for critical contacts and conductors in high-frequency circuits;
• in microwave technology as a coating for the inner surface of waveguides.

The areas of application of silver are constantly expanding, and its applications include not only alloys, but also chemical compounds. A certain amount of silver is constantly consumed for the production of silver-zinc and silver-cadmium batteries, which have very high energy density and mass energy intensity and are capable of delivering very high currents to the load with low internal resistance.

Silver is used as an additive (0.1-0.4%) to lead for casting current collectors of positive plates of special lead-acid batteries that have a very long service life (up to 10-12 years) and low internal resistance.

Silver chloride is used in silver-zinc chloride batteries and in the coatings of some radar surfaces. In addition, silver chloride, which is transparent in the infrared region of the spectrum, is used in infrared optics.

Silver fluoride single crystals are used to generate laser radiation with a wavelength of 0.193 microns (ultraviolet radiation).

Silver is used as a catalyst in gas mask filters.

Silver acetylide (carbide) is occasionally used as a powerful initiating explosive (detonators).

Silver phosphate is used to melt special glass used for radiation dosimetry. The approximate composition of such glass is: aluminum phosphate - 42%, barium phosphate - 25%, potassium phosphate - 25%, silver phosphate - 8%.

Silver permanganate, crystalline dark purple powder, soluble in water; used in gas masks. In some special cases, silver is also used in dry galvanic cells of the following systems: chlorine-silver cell, bromine-silver cell, iodine-silver cell.

Silver is registered as a food additive E174.

In medicine

Main article: Colloidal silver

Until the mid-20th century, silver nitrate was used as a topical antiseptic under the name lapis. In light it decomposes into free silver, nitrogen dioxide and molecular oxygen. However, many significantly more effective antiseptics are now used in all areas.

Since 1990, alternative medicine has seen a resurgence in the use of colloidal silver as a treatment for numerous ailments. Laboratory studies have yielded varying results: some studies have shown that silver has very little antimicrobial effect, while others have shown that a 5-30 ppm solution is effective against staphylococcus and E. coli. This contradiction is associated with the size of colloidal silver nanoparticles - the smaller their size, the more pronounced the antimicrobial effect. It should be noted that similar properties of nanoparticles are characteristic of most transition metals and are associated with the destruction of the bacterial cell membrane during the sorption of nanoparticles. This, however, only appears in very pure solutions.

Silver is a heavy metal, the content of which in drinking water is regulated by SanPiN 2.1.4.1074-01 “Drinking water” - silver is assigned hazard class 2, “highly hazardous substance”. The State Sanitary and Epidemiological Supervision Authority has officially approved hygienic standards for the content of harmful substances in drinking water; in these standards, the silver content in drinking water is limited to a concentration of 0.05 mg/l.

In the USA and Australia, preparations based on colloidal silver are not recognized as medicines and are offered in grocery stores. They can also be found in abundance in online stores around the world as dietary supplements (dietary supplements), a simpler name is food additives. US and Australian law prohibited marketers from attributing medical benefits to colloidal silver. But some sites, including on their territory, still indicate the beneficial effects of the drug in the prevention of colds and flu, as well as therapeutic effects for more serious diseases such as diabetes, cancer, chronic fatigue syndrome, HIV/AIDS, tuberculosis and other diseases. There are no medical studies showing that colloidal silver is effective for any of these reported symptoms.

Before the era of evidence-based medicine, solutions of silver salts were widely used as antiseptics and astringents. The action of such drugs as protargol, collargol, etc., which are colloidal forms of silver, is based on this property of silver. Currently, silver preparations are used less and less due to low efficiency.

Top countries by production

The most recent information I was able to find is for 2017. The list of leaders in silver mining is as follows:

• Mexico - 6108 tons;
• Peru – 4587 tons;
• China - 3502 tons;
• Russia – 1306 tons;
• Chile – 1260 tons;
• Bolivia - 1244 tons;
• Poland - 1228 tons;
• Australia - 1101 tons;
• USA - 1048 tons;
• Argentina – 823 tons.

It is known that the volume of production of this metal around the world continues to decline for the third year in a row. We look forward to the latest results.

Physiological action

Traces of silver (about 0.02 mg/kg) are found in the bodies of all mammals, but its biological role is not well understood. The human brain is characterized by a high content of silver (0.03 mg per 1000 g of fresh tissue, or 0.002% by weight in the ash). Interestingly, in the isolated nuclei of nerve cells - neurons - there is much more silver (0.08% by weight in the ash).

From the diet, a person receives on average about 0.1 mg of Ag per day. Egg yolk contains relatively much of it (0.2 mg per 100 g). Silver is excreted from the body mainly in feces.

Silver ions have bacteriostatic properties. However, to achieve a bacteriostatic effect, the concentration of silver ions in water must be increased so much that it becomes unfit for drinking. The bacteriostatic properties of silver have been known since ancient times. In the 6th century BC. e. The Persian king Cyrus II the Great used silver vessels to store water in his military campaigns. Covering superficial wounds with silver plates was practiced in ancient Egypt. Purification of large quantities of water, based on the bactericidal effect of silver, is especially convenient to carry out electrochemically.

In the early 1970s, the lower limit of the bacteriostatic effect of silver was estimated to be about 1 μg/L in water. According to 2009 data, the lower limit of action is at the level of 50-300 μg/l, which is already dangerous for humans.

Like all heavy metals, silver is toxic when ingested in excess.

According to US health standards, the silver content in drinking water should not exceed 0.05 mg/l. According to current Russian sanitary standards, silver is classified as a highly hazardous substance (hazard class 2 based on sanitary-toxicological hazard), and the maximum permissible concentration of silver in drinking water is the same 0.05 mg/l.

With prolonged intake of excess doses of silver into the body, argyria develops, which is externally expressed as a gray coloration of the mucous membranes and skin, mainly in illuminated areas of the body, which is caused by the deposition of particles of reduced silver. Any well-being disorders in patients with argyria are not always observed. However, non-medical sources noted that they are not susceptible to infectious diseases.

Silver ions have a genotoxic effect, destroying the integrity of DNA molecules in cells, including causing rearrangements in chromosomes and fragmentation of the latter. In addition, the researchers identified gene damage in sperm.

How to spot a fake

There are a couple of simple ways to quickly check the authenticity of a precious metal.

1. Magnet - silver and copper are diamagnetic metals, so they should not be magnetized under any circumstances.
2. Lapis pencil - will not leave marks on the metal, since it is silver nitrate, or, as it is designated in chemistry, AgNO3.
3. Vinegar – Place the item in regular table vinegar. The real thing will not react in any way, and the fake will turn white.
4. Heat - silver will instantly heat up, just put it in boiling water for a moment.

Tips for choosing silver jewelry

When choosing an item, base it on how you want to use it. It is better to choose tableware from metal with a lower grade, but durable. Everyday jewelry is made from sterling alloy, which is what they are most often made from. Items for special occasions can be chosen from high-quality metal: they will be used infrequently, but they will not require special care.

Pathological condition caused by lunar metal

In medical practice, there is an unusual disease called argyria. It appears in a person if for many years of his life he works with silver or its salts. These substances enter the body in small doses, depositing in connective tissues, as well as in the walls of the capillaries of the kidneys, bone marrow and spleen. The pictures below clearly demonstrate the external symptoms of this pathology.

Silver is a metal that gradually accumulates in the mucous membranes and skin, giving them a bluish or gray-green color. At the same time, it becomes especially bright in those areas of the body that are exposed to light. Sometimes the skin color changes so much that the person looks like an African.

The development of argyria occurs very slowly. Its first symptoms become noticeable after two to four years of constant work with silver. The most severe darkening is observed after tens of years. First of all, the color of the lips, temples, and conjunctiva of the eyes changes. Then the eyelids darken. Sometimes the gums and mucous membranes of the oral cavity, as well as the nail holes, become stained. Sometimes argyria appears as small green-blue spots.

It is impossible to get rid of this pathology and return the skin to its previous color. However, apart from external cosmetic inconveniences, the patient does not complain about anything. That is why argyria can only be conditionally considered a disease. This pathology has its own positive side. A person literally soaked in silver never suffers from infectious diseases. Healing ions kill all pathogens entering the body.

Recommendations for care, cleaning and storage

It is recommended to keep silver away from sunlight, in separate bags or cases. Clean the metal at the first sign of plaque, since over time it will become more and more difficult to restore the shine.

Such items require mechanical cleaning, since silver sulfide - that very dark coating on the product - does not dissolve much. To care for your jewelry, you can use toothpaste and a soft brush or napkin and carefully, without pressure, carry out the appropriate manipulations.

Reviews

Lydia:

About ten years ago I bought a silver bar, I recently sold it very profitably, I recommend silver as a financial investment.

Svetlana:

I have always loved silver jewelry more than gold, and they say it’s good for your health.

Gregory:

I bought silverware for the house, we use it, we continue the traditions of our ancestors, although my wife complains that she is tired of cleaning it.

Negative effects of silver

It often happens that a substance that is beneficial to humans in small doses becomes harmful in large quantities. Such elements include silver. It has been experimentally proven that significant volumes of this metal ions can reduce immunity in experimental animals and introduce negative changes into the nervous and vascular tissues of the brain. Even larger doses damage the liver, thyroid gland and kidneys. In practice, cases have been recorded when a person received poisoning from silver preparations, which was accompanied by severe mental disorders. Fortunately, this element is easily eliminated by the body.