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tin
(metal elements)
This entry is compiled and applied by the scientific entry "Popular Science China"? Review.
Tin is a metallic element with silvery white luster and low melting point. It is divalent or tetravalent in compounds and will not be oxidized by air. It mainly exists in the form of dioxide (cassiterite) and various sulfides (such as cassiterite). Element symbol Sn. Tin is a famous "hardware"-one of gold, silver, copper, iron and tin. As early as ancient times, people discovered and used tin. In some ancient tombs in China, tin pots, tin candlesticks and other tin utensils are often excavated. According to research, in the Zhou Dynasty in China, the use of tin ware was very common. Tin daily necessities were also found in ancient tombs in Egypt.
Chinese name: tin
Tin, tin
Chemical formula: Sn
Atomic weight: 1 18.438+0.
Melting point: 23 1.89℃
Boiling point: 2260℃
Atomic number: 50
Si Nuo. : 7440-3 1-5
Period: 5
Mohs hardness: 1.5
Solubility: slightly soluble in water.
Element data
Si Nuo. : 7440-3 1-5
Tin particles in ampoules
Element type: metal element
Atomic volume (cubic centimeter/mole): 16.3
Element content in the sun: (ppm) 0.009
Element content in seawater: (ppm) Atlantic surface 0.0000023.
Content in the shell: (ppm) 2.2
Oxidation state:
Sn+2，Sn+4
Atomic number: 50
Number of protons: 50
silver paper
Molar mass:119g/mol.
Number of families: IVA
Electron layer arrangement: 2-8- 18- 18-4.
Nuclear power cost: 50 pounds
Electronic arrangement:1s222p63p2p63d104s24p64d105s25p2.
Peripheral electron layer arrangement: 5s2 5p2
Electron layer: K-L-M-N-O
The speed of sound propagation in it: (m/s) 2730
Chemical bond energy
Unit (kJ/mol)
Sn-H 3 14Sn-C 225
Sn+2-O 557
Sn+4-F 322
Sn+4-Cl 3 15
Serial number 195
Ionization energy
Unit (kJ/mol)
Male-male+708.6
Chu Hsi
M+ - M2+ 14 1 1.8
M2+ - M3+ 2943
M3+ - M4+ 3930.2
M4+ - M5+ 6974
M5+ - M6+ 9900
M6+ - M7+ 12200
M7+ - M8+ 14600
M8+ - M9+ 17000
M9+ - M 10+ 20600
Lattice parameters
a = 583. 18 pm
Tin artware
b = 583. 18 pm
c = 3 18. 19 pm
α = 90
β = 90
γ = 90
Element attribute
Tin is a carbon group element with atomic number 50 and atomic weight 1 18.7 1. Element names come from Latin. Around 2000 BC, humans began to use tin. The content of tin in the earth's crust is 0.004%, almost all of which exists in the form of cassiterite (tin oxide), in addition to a very small amount of tin sulfide ore. The isotope of tin is 14, in which 10 is a stable isotope, namely: tin 1 12,14, 1 15,/.
Tin is soft and flexible, with a melting point of 23 1.89℃ and a boiling point of 2260℃. There are three kinds of allotropes:
White tin is tetragonal, and its unit cell parameters are: a=0.5832nm, c=0.3 18 1nm. The unit cell contains four tin atoms, the density is 7.28 g/cm3, the hardness is 2, and the ductility is good.
Gray tin is a rhombic cubic crystal system, and its unit cell parameter is: a=0.6489nm, and the unit cell contains 8 Sn atoms with a density of 5.75 g/cm3.
Brittle tin is orthorhombic with a density of 6.54 g/cm3.
The tin dioxide protective film is stable on the tin surface in the air, and the oxidation reaction is accelerated by heating; Tin reacts with halogen under heating to generate tin tetrahalide; It can also react with sulfur; Tin is stable to water, and can be dissolved slowly in dilute acid and rapidly in concentrated acid. Tin can be dissolved in strong alkali solution; It will be corroded in acidic solution of ferric chloride, zinc chloride and other salts.
Tin is a silvery white soft metal with a specific gravity of 7.3 and a low melting point of only 232℃. If you put it in a briquette furnace, it will melt into liquid like mercury. Tin is so soft that you can cut it with a knife. The chemical properties of tin are very stable, and it is not easy to be oxidized by oxygen at room temperature, so it often keeps shiny silver. Tin is non-toxic, so people often plate it on the inner wall of copper pot to prevent copper and warm water from forming toxic copper rust (basic copper carbonate). Toothpaste shells are often made of tin (toothpaste shells are made of two layers of tin with a layer of lead in the middle). In recent years, China has gradually replaced tin with aluminum to make toothpaste shells. Solder also contains tin, generally containing 6 1% tin, some of which are half lead and half tin, and some of which are composed of 90% lead, 6% tin and 4% antimony.
forgeability
Tin is malleable at room temperature. Especially at the temperature of 100℃, it has very good ductility and can be developed into extremely thin tin foil. Usually, people pack cigarettes and sweets with tin foil to prevent them from getting wet (in recent years, China has gradually replaced tin foil with aluminum foil. Aluminum foil and tin foil are easy to distinguish-tin foil is much brighter than aluminum foil). However, the ductility of tin is very poor. When it is pulled, it will break and cannot be drawn into filaments.
In fact, tin is malleable only at room temperature. If the temperature drops below-13.2℃, it will gradually become loose powder like coal ash. Especially at -33℃ or in the presence of alcohol solution with red salt (sncl 4·2 NH 4 cl), the speed of this change is greatly accelerated. A good tin pot will automatically turn into a pile of powder. This tin "disease" can also be transmitted to other "healthy" tin utensils, which is called "tin epidemic". The reason of tin plague is that the crystal lattice of tin has changed: at room temperature, tin has a tetragonal crystal structure, which is called white tin. When you bend a tin bar, you can often hear a crack. This is because the square white tin crystals rub against each other when bending and make a sound. When the temperature is lower than-13.2℃, white tin is transformed into amorphous gray tin. As a result, the tin turned into a mass of powder.
Since tin is afraid of cold, special attention should be paid not to freeze tin in winter. There are many ironware that are usually soldered with tin and won't freeze. 19 12 years, a foreign Antarctic expedition went to explore the Antarctic, and the petrol tanks used were all soldered. In the Antarctic ice and snow, solder turned into powdered gray tin, and gasoline leaked out.
Tin is not only afraid of cold, but also of heat. Above 16 1℃, white tin is transformed into rhombohedral tin with rhombohedral crystal structure. Oblique tin is brittle, it will break when knocked, and its ductility is poor. It is called "brittle tin". White tin, gray tin and brittle tin are three allotropes of tin.
Tin is inert and does not react with air and water. React with concentrated hydrochloric acid to generate stannous chloride; It does not react with dilute sulfuric acid, but with concentrated hot sulfuric acid to produce tin sulfate (ⅳ); Using concentrated hot nitric acid to produce β-stannic acid. [ 1]?
Source use
Tin is a famous "hardware"-one of gold, silver, copper, iron and tin. As early as ancient times, people discovered and used tin. In some ancient tombs in China, tin pots, tin candlesticks and other tin utensils are often excavated. According to research, in the Zhou Dynasty in China, the use of tin ware was very common. Tin daily necessities were also found in ancient tombs in Egypt.
China is rich in tin resources, especially Gejiu, a world-famous "tin capital". In addition, Guangxi, Guangdong and Jiangxi provinces also produce tin. 1800 The annual output of tin in the world was only 4,000 tons, 1900 was 85,000 tons, and 1940 was 250,000 tons. Now it has exceeded 600,000 tons.
But arsenic is associated with tin, and its compound is the main component of arsenic.
According to the paper published by the Environmental Restoration Research Center of Institute of Geographical Sciences and Resources, Chinese Academy of Sciences, arsenic, as an associated ore of tin, has become abandoned tailings because of its low utilization value. By 2008, at least 1 167000 tons of arsenic remained in the environment in China, which is equivalent to millions of tons of arsenic scattered in the wilderness, washed by rain, injected into rivers and infiltrated into soil.
use
Metal tin is mainly used to make alloys.
Tin sulfide is a compound of tin and sulfur, which is similar in color to gold and is often used as a gold pigment.
Tin dioxide, compounds of tin and oxygen. Tin is not oxidized in air at room temperature, but becomes tin dioxide when heated strongly. Tin dioxide is a white powder insoluble in water, which can be used to make enamel, white glaze and opalescent glass. Since 1970, people have used it to prevent air pollution-automobile exhaust often contains toxic carbon monoxide gas, but most of it can be converted into carbon dioxide at 300℃ under the catalysis of tin dioxide.
Tin ware has a long history, dating back to 3700 BC. In ancient times, people often put tin blocks at the bottom of the well to purify water. In the Japanese court, all the carefully brewed royal wines are made of tin utensils. It has the characteristics of unchangeable brown color, warm in winter and cool in summer, and honest and refreshing. Tin teapot is especially fragrant for making tea. It is cool to drink with tin cup, and the tin vase flower arrangement is not easy to wither. At the end of 18 and the beginning of 19, tin was used as a fresh-keeping tank.
The material of tin ware is alloy, in which the content of pure tin is above 97%, and it does not contain lead, so it is suitable for daily use. Tin ware has always been favored by nobles and become a symbol of European classical culture because of its warm and smooth characteristics, noble and elegant shape and lasting new luster.
Tin is the fourth precious metal after platinum, gold and silver. Glossy, non-toxic, not easy to be oxidized and discolored, with good sterilization, purification and preservation effects. Commonly used in food preservation, canned inner anti-corrosion film and so on.
Tin is a soft metal with low melting point and strong plasticity. It can have a variety of surface treatment processes, and can be made into a variety of products, including traditional and elegant European-style wine sets, candlesticks, noble and elegant tea sets, and even eye-catching vases and exquisite table ornaments, all of which can be comparable to sparkling silverware. Tin ware has long been popular all over the world for its elegant appearance, unique function and practicality, and has become a good product for people's daily necessities and gifts to relatives and friends.
In ancient China, tin was often used to make bronze. The ratio of tin to copper is 3: 7.
Elemental history
Metallic tin
Tin has a direct impact on human history, mainly because of bronze, but it can also be used as itself. A tin ring and a pilgrimage bottle were found in the tomb of the18th dynasty (BC 1580- 1350) in Egypt. About 700 BC, China people mined tin in Yunan Province. Pure tin was also found in Machu Picchu, a castle in the Inca Mountains.
When copper is alloyed with about 5% tin, bronze will be produced, which not only reduces the melting point, but also is easier to process, but the produced metal will be harder, making it an ideal material for making tools and weapons. The Bronze Age is a recognized stage of civilization development. We don't know how bronze was invented, but people in Egypt, Mesopotamia and the Indus Valley began to use it around 3000 BC.
Tin, tin, is an old English word. The symbol of Sn comes from tin, which is the Latin name of tin and was found in prehistoric times. Because it won't rust and can resist external erosion, canned instruments have to be used. Canned food is made of tin plated with 0.0005 inch thickness on iron sheet. The annual output of tin cans is at least 30 billion.
In nature, tin rarely exists in a free state, so there is little pure metal tin. The most important tin ore is cassiterite, and its chemical composition is tin dioxide. Tin smelting is easier than copper smelting, iron smelting and aluminum smelting. As long as cassiterite and charcoal are burned together, charcoal will reduce tin in cassiterite. Obviously, if ancient people burned bonfires and wild animals in places with tin mines, the cassiterite on the ground would be reduced by charcoal and the silver molten tin would flow out. Because of this, tin was discovered long ago.
The earliest metal discovered by human beings is gold, but it has not been widely used. However, the earliest discovered and widely used metals are copper and tin. The alloy of tin and copper is bronze, with lower melting point, better castability and higher hardness than pure copper. Therefore, as soon as they were discovered by human beings, they were widely used and wrote a brilliant page in the history of human civilization. This is the "Bronze Age". Later, due to the discovery and use of iron, bronze gradually retreated to the second line in the production and life of our ancestors. However, this does not make tin insignificant in the history of human development. On the contrary, with the rapid development of modern science and technology, it has been more and more widely used in industrial and agricultural production and cutting-edge science and technology departments, and ancient metals are becoming more and more youthful!
In the crust, the content of tin is relatively small, with an average content of only 0.004%, so tin is a rare and expensive metal. After years of research, it has been proved that the formation of tin deposits is closely related to magmatism in the deep crust.
About 70 million years ago to 1 100 million years ago, the magma activity on the earth was intense. When magma rises from deep underground, due to the changes of temperature and pressure, some easily solidified minerals in magma crystallize first, and the rest of residual magma intrudes into rock gaps, and tin compounds in it are hydrolyzed to form tin-bearing cassiterite. Some of them continue to move upward, especially the magma containing a lot of volatile substances, which is particularly active. They are like high-pressure steam in a boiler, drilling around cracks and everywhere. Tin has a "quirk", that is, it likes to "make friends" with volatile substances such as fluorine and chlorine, and they combine to form volatile compounds. When these gas-liquid substances intrude into the surrounding rock along the cracks, due to the displacement reaction of substances under high temperature and high pressure, a part of tin elements crystallize and precipitate to form tin deposits; At this time, the last part of the gas-liquid containing volatile substances continues to move forward until it rushes to the top of the solidified granite or outside the granite body and gradually becomes a hot water solution. At this time, due to the change of environment, fluoride and chloride of tin are hydrolyzed at the same time, and tin deposits are also formed. Of course, the above is not all the causes of tin mines. Sometimes, near the surface, due to the long-term effect of oxygen and carbon dioxide in groundwater, sulfide minerals associated with tin will become oxide minerals, thus becoming cassiterite-oxide deposits.
What I have introduced to you above is only the general genesis of primary tin deposits. However, the evolution of tin deposits has not stopped, especially the tin deposits near the surface will further evolve into "secondary tin deposits" under the weathering, erosion, transportation and accumulation of external forces.
In addition, tin will combine with many minerals to form a * * * tin deposit.
At present, about 18 kinds of tin minerals have been discovered. The most important one is cassiterite, which is the main raw material for tin smelting at present. In nature, pure cassiterite is rare, and the most common cassiterite is dark brown black or brown, because they contain elements such as iron and manganese. Cassiterite is too hard to carve with a knife; In addition, the chemical properties of cassiterite are very stable, and it is almost insoluble in any chemical solvent at normal temperature and pressure. So cassiterite was destroyed by wind, sword, frost and rain. The appearance remains the same.
Cassiterite is not tin yet. Cassiterite is mined from the ground through the hard work of miners. The impurities contained in cassiterite are removed by various methods, and then cassiterite is burned with coke, timely or limestone to finally obtain metallic tin.
Tin is so soft that you can cut it with a knife. It has a silvery white luster and good ductility. It can be developed into extremely thin tin foil, and the thickness can be as thin as 0.04 mm or less. However, its ductility is poor, and it will break when it is pulled, and it cannot be pulled into filaments. Its melting point is very low, only 232℃, so it can be melted into a liquid as liquid as mercury with alcohol lamp or candle flame.
In addition, tin is afraid of both cold and heat. What's going on here? It turns out that tin has three different forms at different temperatures. In the temperature range of-13.2 ~161℃, the properties of tin are the most stable, which is called "white tin". If the temperature rises above 160℃, white tin will become brittle when touched. Tin is very sensitive to cold. When the temperature is lower than-13.2℃, it will gradually change from silvery white to a kind of coal ash powder, which is called "gray tin". In addition, there is an interesting phenomenon in the transition from white tin to gray tin, that is, gray tin is "contagious". As long as white tin meets gray tin, even a small spot, white tin will immediately turn into gray tin until the whole piece of white tin is destroyed. People call this phenomenon "tin plague". Fortunately, this disease can be treated. If the diseased tin melts again, it will recover.
There was such a thing in history: 19 12, Scott, Bowles, Wilson, Evans and Oates explored the frozen Antarctic, and all the gasoline they carried with them was strangely leaked, resulting in fuel shortage and the expedition was wiped out. It turned out that the petrol tank was welded with tin, and a tin epidemic made the petrol leak without a trace, which caused such a tragic disaster.
So, what's the use of tin that is afraid of both heat and cold?
Metal tin can be used to make all kinds of tin products and works of art, such as tin pots, tin cup, tin tableware and so on. Many tin products and artworks made in China have been sold well in many countries since ancient times and are deeply loved by people in these countries.
Metal tin can also be made into tin tubes and foil, which can be used in food industry to ensure cleanliness and non-toxicity. Such as tin foil for packaging candy and cigarettes, which is moisture-proof and beautiful.
One of the important uses of metallic tin is to manufacture tin-plated iron sheets. Once a piece of iron sheet is covered with an iron "coat", it can prevent corrosion and virus. This is because the chemical properties of tin are very stable and it is difficult to react with water, acid and alkali. At present, tin plating is not only widely used in food industry, such as canning industry, but also in many departments such as military industry, instrumentation, electrical appliances, light industry and so on.
In industry, tin is often plated on copper wire or other metals to prevent these metals from being corroded by acid and alkali.
Tin also has many relatives and friends. When tin is mixed with them, a variety of alloys with different properties and wide uses can be synthesized. The most common alloys are tin-based bearing alloys composed of tin and antimony copper and lead-based bearing alloys composed of lead, tin and antimony, which can be used to manufacture bearings for high-speed and high-pressure mechanical equipment such as steam turbines, generators and airplanes.
Bronze is an ancient alloy, which is mainly used to manufacture wear-resistant parts and corrosion-resistant equipment.
If tin is added to brass, it becomes tin brass, which is mostly used to manufacture ship parts and welding belts. Known as "navy brass".
As for the alloy of tin and lead, it is the most familiar one. It is a commonly used solder and is very useful in welding metal materials.
In the printing house, the type used is tin alloy. However, due to the popularity of laser printing technology, this type will be gradually eliminated.
Tin can not only combine with many metals to form various alloys, but also combine with many nonmetals to form various compounds, which has made due contributions in chemical industry, dye industry, rubber industry, enamel, glass, plastic, paint, pesticide and other industries.
With the development of modern science and technology, people have also made many special tin alloys from tin, which are used in advanced technical departments such as atomic energy industry, electronics industry, semiconductor devices, superconducting materials, spacecraft manufacturing and so on, so I won't go into details here.
China is rich in tin resources, with proven reserves of 26 million tons, accounting for 1/4 of the world's proven reserves. It is the country with the largest proven reserves of tin mines in the world.
Tin mines in China are very uneven in regional distribution, mainly distributed in southern Yunnan, northeastern Guangxi and northwestern Guangxi. Followed by Guangdong, Hunan and Jiangxi provinces. Gejiu City, located in Ailaoshan District, Yunnan Province, is one of the largest known tin mines in the world, and its tin production ranks first in China, accounting for about 70% of the national tin production. It is called "Tin Capital".
In short, tin, an ancient metal. Today, with the rapid development of modern science and technology, its uses will be more and more extensive and its prospects will be broader and broader.
Tin is one of the oldest metals in mankind. With the continuous expansion of industrial uses of tin, the mining, mineral processing, smelting and processing of tin have developed rapidly, and a complete tin industry has gradually formed. Today, ancient tin is still an indispensable key rare metal in modern industry. It is called "industrial monosodium glutamate" and is widely used in electronics, information, electrical appliances, chemical industry, metallurgy, building materials, machinery, food packaging and other industries. Tin resources in the world are mainly distributed in China, Indonesia, Peru, Brazil, Malaysia, Bolivia, Russia, Thailand and Australia. By 20 1 1 year, the discovered resources of China tin mine are about 1.5 million tons, accounting for 28.85% of the world. Tin mines in China are mainly concentrated in Yunnan, Guangxi, Hunan, Inner Mongolia, Guangdong and Jiangxi, and the reserves of tin mines in these six provinces account for about 98% of the country's proven resources.
After the strong recovery of refined tin consumption in China at 20 10, the overall consumption at 201/kloc-0 entered a stable period. From 20 1 1 to 65438+February, the national cumulative tin output was 155855.34 tons, up 4.89% year-on-year. 2012-1-June, the national cumulative tin output was 70 156.87 tons.