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Element Name: Silver Element Symbol: Ag
English name of element: Silver
Element type: Metal Relative atomic mass: 107.9
Atomic number:47
Number of protons:47
Molar mass: 108
Ownership period: 5
Family membership: IB
Electronic layer arrangement: 2-8-18-18-1
Common valence: +1
Elemental: Silver Elemental Chemical Symbol: Ag
Color and Status: Silver White Metal
Mohs hardness: 2.5
Sound propagation speed in it: (m/S)
2680
Density: 11.7 g/cm3
Melting point: 961.93°C
Boiling point: 2213°C
Other properties: It is rich in ductility and is a metal with good thermal and electrical conductivity. The first ionization energy is 7.576 eV. Chemically stable, it has no effect on water and oxygen in the atmosphere; soluble in dilute nitric acid, hot concentrated sulfuric acid and hydrochloric acid, molten alkali hydroxide.
Crystal structure: The unit cell is a face-centered cubic unit cell, and each unit cell contains 4 metal atoms.
I. The nature of silver:
Silver is one of the metals discovered in ancient times. Although silver also exists in nature, it is mostly in the form of chemical compounds.
Silver has a high degree of ductility, so it can be rolled into a 0.00003 cm thick transparent foil. A 1 gram silver pellet can be drawn into filaments about two kilometers long.
Silver has the highest thermal conductivity and electrical conductivity among metals.
The characteristic oxidation number of silver is +1. Its chemical properties are worse than that of copper. At room temperature, even when heated, it does not interact with oxygen in water and air, but it can become black in the air for a long time and lose its silver-white luster. This is Silver and air in the H2S synthetic black Ag2S reason. The chemical reaction equation is:
4Ag + H2S + O2 = 2Ag2S + 2H2O
Silver cannot react with dilute hydrochloric acid or dilute sulfuric acid to release hydrogen, but silver can dissolve in nitric acid or hot concentrated sulfuric acid:
heating
2Ag + 2H2SO4 (concentrated) ==== Ag2SO4 + SO2↑ + 2H2O
Silver reacts very slowly with halogen at room temperature, and halides are formed under heating conditions:
473K
2Ag + F2 ===== 2AgF dark brown
heating
2Ag + Cl2 ===== 2AgCl↓ White
heating
2Ag + Br2 ===== 2AgBr↓ yellow
heating
2Ag + I2 ===== 2AgI↓ Orange
Silver has a strong affinity for sulfur and can be synthesized directly with sulfur to Ag2S when heated:
heating
2Ag + S ==== Ag2S
II. Application of silver:
Pure silver is a beautiful silver-white metal, it has good ductility, its electrical conductivity and heat transfer are the highest in all metals.
For example, if the conductivity of mercury is 1, the conductivity of copper is 57, and the conductivity of silver is 59, which is the highest. Therefore, silver is often used to make extremely sensitive physical instrument components, various automation devices, rockets, submarines, computers, nuclear devices, and communication systems. A large number of contact points in all these devices are made of silver. During use, each contact must work millions of times, must be wear-resistant and reliable, can withstand strict work requirements, silver can fully meet all kinds of requirements. If you add rare earth elements to silver, the performance will be even better. With this contact point made of silver added rare earth elements, life can be extended several times.
Of all the metals, silver has the best reflection of natural light. Silver therefore plays an important role in the mirror industry.
In addition, silver ions can be sterilized. Herdsmen in the Inner Mongolia area of ​​China often use silver bowl Shengma milk, which can be stored for a long time without becoming sour.
Element source:
Silver mines mainly include silver and silver mines, followed by horn mines and natural silver. The silver ore is co-heated with salt and water, then combined with mercury as silver amalgam, and mercury is distilled off to obtain silver. Or by the silver ore to cyanide alkali leaching lead or zinc precipitation made of silver.
Elemental use:
Used for making alloys, solders, silver foils, silver salts, chemical instruments, etc., and used in making silver coins and silver.
The most important compound of silver is silver nitrate. In medical treatment, aqueous solutions of silver nitrate are commonly used as eye drops because silver ions can strongly kill germs.
The price is generally around 70 yuan/g and the purity is 999. Silver nitrate breaks out silver when exposed to light or organic matter. Silver is grayish black if it is tiny particles. This compound is used to plate silver or to make other silver compounds. It is also the main raw material for the photosensitive layer of photographic negatives. ㄈ芤嚎      îŸ æ©¹î‡˜îƒ¡æ¹ŽâˆªèŠ¤åšŽæŽç³œ 橹湎∪芤嚎æŽç³œ 橹湎∪芤嚎æŽç³œ 橹湎∪芤嚎æŽç³œ 橹湎∪芤嚎æŽç³œ 橹湎∪芤嚎æŽç³œ 橹湎∪芤嚎æŽç³œ 橹湎∪芤嚎æŽç³œ 橹湎∪芤嚎æŽç³œ?
Silver oxide is easily dissolved in ammonia water. After the solution is left for a long time, black crystals with strong explosiveness are sometimes precipitated. Silver oxide is used as a colorant in the glass industry.
The photosensitizing effect of silver bromide is used to make the photosensitive layer of a photographic film.
III. History of silver:
In ancient times, humans knew silver. Like gold, silver is a precious metal with a long history of application. It has a history of more than 4,000 years. Because of the unique characteristics of silver, people gave it the double value of money and decoration. The British pound and the silver dollar used before China’s liberation were silver and copper alloys.
Silvery white, with soft and bright luster, is a favorite decoration for ethnic minorities, Buddhists and Muslims. Silver jewellery is also the gift of choice given by the people of all ethnic groups in the country to newborn babies. Recently, people in Europe and America have been wearing silver-inspired turquoise blue jewelry that is easily oxidized and darkened under the influence of retro trend of thought. This brings to mind the infinite beauty of ancient civilization. In China, sterling silver jewellery has gradually become a favorite choice of modern fashion women. Silver is one of the metals that was already known in ancient times. Silver is more lively than gold. Although its abundance in the earth's crust is about 15 times that of gold, it rarely exists as a simple substance, so its discovery is later than gold. In ancient times, people already knew about the mining of silver mines, because the amount of silver that people obtained at that time was very small, making it worth more than gold. Between 1780 and 1580 BC, the code of the Egyptian dynasty provided that the value of silver was twice that of gold. Even in the 17th century, the value of Japan’s gold and silver was equal. Silver was first used as a decoration and tableware, and later used as a currency.
Sterling silver is a beautiful white metal, the silver chemical symbol Ag, from its Latin name Argentum, is "light, bright". Its English name is Silver. Silver has a high degree of ductility and can be rolled into a 0.000003 cm thick transparent foil. A 1 g weight of silver can be drawn into filaments of about 2 km.
Moon-like metal - silver
Silver will always shine like a moon. Silver's thesis will mean "bright." China also uses silver words to describe white and glossy things, such as the galaxy, ginkgo, silver fish, white fungus, and silver screens.
In ancient China, silver was often juxtaposed with gold and copper, and was called "Jin Jin San Pin." The book “Gongong†records “Jin Jin San Pinâ€. It can be seen that China found silver as early as the 23rd century BC, that is, more than 4,000 years ago. In nature, silver often exists in the form of pure silver, and people have found a piece of pure silver weighing 13.5 tons! In addition, it exists in the form of chlorides and sulphides and is often symbiotic with lead, copper, antimony, arsenic and other minerals.
IV. Elemental supporting information:
Silver rarely exists as a simple substance in nature, and most of it is a compound state. Therefore, its discovery is later than that of gold. It is generally considered that it is 5500-6000 years ago. Nekrasov’s “General Chemistry Course†also talks about natural silver. The largest silver block ever discovered weighs 13.5 tons.
Natural silver is mostly alloyed with gold, trigonum, tantalum, copper or platinum. Natural gold is almost always alloyed with a small amount of silver. Known in ancient China as amber gold, known as ELECTRUM in English, is a natural gold and silver alloy containing approximately 20% silver. Initially due to the small amount of silver that people obtained, it was worth more than gold. In the Egyptian dynasty code of about 1780-1580 BC, silver was worth twice as much as gold. Even in the 17th century, the value of silver and gold in Japan is still equal. In “Critique of Political Economyâ€, Marx stated: “...and the exploitation of silver is based on the premise of mining labor and generally more advanced technological development. Therefore, although silver is not so inexorably thin, its initial value is relatively low. Greater than the value of gold."
By the 13th to 14th century, both China and Europe had developed a method of testing gold and silver. This is also a method of separating impurities in gold and silver, also known as metallurgical method. In this method, gold or silver samples to be inspected or gold and silver collected are placed in a crucible made of animal ashes. Lead and other impurities form oxides, some of which are blown away by air, and some of them are infiltrated into ash. In the middle, unoxidized gold and silver are left behind. In this way, the amount and purity of gold and silver in the sample or gold can be calculated. This method has so far also been used in analytical chemistry.
Silver is called platinum in ancient China. Ancient Western people used the symbol of the moon to represent silver. In Latin, “silver†is argentum, from the Greek argyros (bright). Therefore, the chemical symbol of silver is Ag.
Herdsmen in Inner Mongolia, China, commonly used silver bowl Shengma milk, can be long-term preservation without acid. According to research, this is due to a very small amount of silver dissolved in water in the form of silver ions. Silver ions can sterilize and only contain 100 billion parts of silver ions per liter of water, enough to kill most bacteria. Ancient Egyptians also knew that silver tablets were covered in wounds and sterilized more than 2,000 years ago. For the time being, people used silver wire to sliver silver “gauze†and wrap wounds to treat certain skin wounds or refractory ulcers.
Silver does not combine directly with oxygen and is chemically stable. Strangely, in February 1902, on the Martini Island near Cuba in Latin America, silverware darkened within a few days. Later, it was discovered that the original volcano broke out and that the volcanic gas contained a small amount of hydrogen sulfide, which reacted with silver to produce black silver sulfide. Normally, trace amounts of hydrogen sulfide are also contained in the air. Therefore, the silverware is left in the air for a long time, and the surface becomes darker and darker. In addition, the air contains traces of ozone, which can also interact directly with silver to produce black silver oxide. Because of this, the ancient silverware is now not as bright as the ancient gold. However, silver-palladium alloys containing 30% palladium are often used to make dentures and accessories in cases where hydrogen sulfide is not black.
Silver does not corrode in dilute hydrochloric acid or dilute sulfuric acid. However, hot concentrated sulfuric acid and concentrated hydrochloric acid can dissolve silver. As for nitric acid, silver is more soluble. However, silver is alkali-resistant, so silver hydrazine is commonly used in chemical laboratories to melt potassium hydroxide or sodium hydroxide.
Silver, like gold, is also a “nobility†in metals and is called “precious metalâ€. It used to be used only as money and decorations. Nowadays, silver has three important uses in the industry: electroplating, mirror making and photography.
A layer of silver plating on some easily rusted metal surfaces can extend the service life and make it beautiful. When silver is plated, silver is the positive electrode, and the workpiece is the negative electrode. However, silver nitrate solution cannot be directly used as the electrolyte because the concentration of silver ions is too high, the plating speed is fast, the silver deposition is fast, and the silver plating is very loose. Pieces fall off. In general, cyanide is added to the electrolyte, because the cyanide ion can form a complex with silver ions, which reduces the concentration of silver ions in the solution, reduces the deposition rate of the negative electrode silver, and improves the plating quality. As the silver folds out, the concentration of silver ions in the electrolyte drops, and then the cyanide ions continue to dissociate, and the silver ions are continuously transferred to the solution, so that the silver ions in the solution always maintain a certain concentration. However, cyanide poisoning is a big drawback.
The glass mirror is shiny silver, and the back is evenly plated with a layer of silver. However, this silver is not plated by the electroplating method, but is plated by the “silver mirror reactionâ€: the ammonia solution of silver nitrate is poured into the glucose solution. Glucose is a reducing agent. (Now the mirror factory also has Using formaldehyde and ferrous chloride as reducing agents, it can reduce the silver in silver nitrate to silver metal, precipitate on glass, and make a mirror. The thermos bile is also shiny and silver-plated.
Silver is of particular importance in the manufacture of photosensitive materials for photography. Because photo paper, film coated with sensitizers, are all silver compounds - silver chloride or silver bromide. These silver compounds are very sensitive to light. As soon as they were illuminated they broke down. The light is much more decomposed where the light is strong, and the light is weak. However, the “image†at this time is only vaguely visible and must be revealed before it becomes clear and stable. After development, it is subjected to fixing to remove excess silver chloride or silver bromide that has not been exposed to the film. The image on the film is opposite to the real image. It is called a negative film—where light is strong, silver chloride or silver bromide is much more degraded, and black is darker (the dark matter on the negative film is very fine metallic silver), but the light is weak. It looks white. When printing a photo, the black and white of the photo is the opposite of the negative, so it matches the real tone. Modern photography technology has been able to shoot very clear photos in the light of a weak match, in a few tens of to a few hundredths of a second. Today, there are 150 tons of silver used for film and photography every year in the world.
The overall profile of Silver: