Who discovered the chemical element tellurium. The structure of the tellurium atom

DEFINITION

Tellurium is the fifty-second element of the Periodic Table. Designation - Te from the Latin "tellurium". Located in the fifth period, VIA group. Belongs to the family of metalloids. The core charge is 52.

Tellurium is one of the rare elements: its content in the earth's crust is only 0.000001% (mass).

In its free form, tellurium is a metal-like crystalline substance of silver-white color (Fig. 1) with a hexagonal lattice. Brittle, easily rubbed into powder. Semiconductor. Density 6.25 g/cm 3 . Melting point 450 o C, boiling point 990 o C.

Existence in an amorphous state is known.

Rice. 1. Tellurium. Appearance.

Atomic and molecular weight of tellurium

The relative molecular weight of a substance (M r) is a number showing how many times the mass of a given molecule is greater than 1/12 of the mass of a carbon atom, and the relative atomic mass of an element (Ar r) is how many times the average mass of atoms of a chemical element is greater than 1/12 the mass of a carbon atom.

Since tellurium exists in the free state in the form of monatomic Te molecules, the values ​​of its atomic and molecular masses coincide. They are equal to 127.60.

Isotopes of tellurium

It is known that tellurium can occur in nature in the form of eight stable isotopes, two of which are radioactive (128 Te and 130 Te): 120 Te, 122 Te, 123 Te, 124 Te, 125 Te and 126 Te. Their mass numbers are 120, 122, 123, 124, 125, 126, 128 and 130 respectively. The nucleus of the tellurium isotope 120 Te contains fifty-two protons and sixty-eight neutrons, and the other isotopes differ from it only in the number of neutrons.

There are artificial unstable isotopes of tellurium with mass numbers from 105 to 142, as well as eighteen isomeric states of nuclei.

tellurium ions

At the outer energy level of the tellurium atom, there are six electrons that are valence:

1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2 5p 4 .

As a result of chemical interaction, tellurium gives up its valence electrons, i.e. is their donor, and turns into a positively charged ion or accepts electrons from another atom, i.e. is their acceptor and turns into a negatively charged ion:

Te 0 -2e → Te +;

Te 0 -4e → Te 4+;

Te 0 -6e → Te 6+;

Te 0 +2e → Te 2- .

Tellurium molecule and atom

In the free state, tellurium exists in the form of monatomic Te molecules. Here are some properties that characterize the tellurium atom and molecule:

Examples of problem solving

EXAMPLE 1

EXAMPLE 2

Exercise	Calculate the mass fractions of the elements that make up tellurium dioxide if its molecular formula is TeO 2 .
Solution	Mass fraction element in the composition of any molecule is determined by the formula: ω (X) = n × Ar (X) / Mr (HX) × 100%.

Physical Properties
Tellurium exists in two modifications - crystalline and amorphous.
Crystalline tellurium is obtained by cooling tellurium vapor, and amorphous tellurium is obtained by reducing telluric acid with sulfur dioxide or another similar reagent:

Amorphous tellurium is a fine black powder that transforms into metallic tellurium when heated. The density of amorphous tellurium is 5.85-5.1 g/cm3.
For crystalline tellurium, two polymorphic varieties are known: α-Te and β-Te. The α→β transition occurs at 354°C. Crystalline tellurium has a white-silver color. Its density is 6.25 g/cm2. Hardness of crystalline tellurium 2.3; at ordinary temperatures it is brittle, easily broken into powder, and at higher temperatures it becomes so plastic that it can be pressed.
The melting point of tellurium is 438-452 ° C, and the boiling point is 1390 ° C. Tellurium is characterized by high vapor pressure, which, depending on temperature, is expressed by the following numbers:

Tellurium has a semiconductor nature of conductivity. The electrical resistance of polycrystalline tellurium at 0°C is 0.102 ohm*cm. With increasing temperature, the electrical resistivity of tellurium decreases:

In contrast to selenium, the electrical resistance of tellurium is not very sensitive to illumination. However, at low temperatures, the influence of lighting still affects; so, at -180 ° C, the electrical resistance of tellurium under the influence of illumination decreases by 70%.
Chemical properties
By their own chemical properties tellurium is similar to selenium, but has a more pronounced metallic character. At room temperature, compact tellurium is resistant to air and oxygen, but when heated, it oxidizes and burns with a blue flame with a green border, forming TeO2.
In the dispersed state and in the presence of moisture, tellurium is oxidized at ordinary temperatures. Tellurium reacts with halogens at room temperature and forms chemically stronger halides (TeCl4; TeBr4) than selenium.
Tellurium does not combine directly with hydrogen under ordinary conditions, but when heated, it forms H2Te. When heated with many metals, tellurium forms tellurides: K2Te, Ag2Te, MgTe, Al2Te, etc.
Metallic tellurium reacts with water at 100-160°C, and freshly deposited (amorphous tellurium) at room temperature:

Te + 2H2O → TeO2 + 2H2.

Tellurium does not dissolve in CS2; dissolves very slowly in dilute HCl. In concentrated and dilute HNO3, tellurium is oxidized to form H2TeO3:

3Te + 4HNO3 + H2O = 3H2TeO3 + 4NO.

Tellurous acid is easily decomposed by sulfur dioxide with the release of tellurium:

H2TeO3 + 2SO2 + H2O → Te + 2H2SO4.

This reaction is used to obtain pure tellurium.
Tellurium is an almost constant companion of heavy non-ferrous metals in sulfides (iron and copper pyrites, lead luster), but it also occurs in the form of minerals sylvanite, calaverite (Au, Ag)Te2, etc.
The main source of industrial tellurium is the waste processing of sulfide ores of copper and lead - dust, in which tellurium is present in the form of TeO2, obtained by roasting sulfide ores; as well as anode sludge obtained from the electrolytic refining of copper and lead.

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Oud. heat of fusion

17.91 kJ/mol

Oud. heat of evaporation

49.8 kJ/mol

Molar heat capacity The crystal lattice of a simple substance Lattice structure

hexagonal

Lattice parameters

a =4,457 c =5,929

Attitude c/a Other characteristics Thermal conductivity

(300 K) 14.3 W/(m K)

Native tellurium is also found together with selenium and sulfur (Japanese telluric sulfur contains 0.17% Te and 0.06% Se).

Deposit types

Most of the mentioned minerals are developed in low-temperature gold-silver deposits, where they are usually isolated after the main mass of sulfides together with native gold, silver sulfosalts, lead, and also with bismuth minerals. Despite the development of a large number of tellurium minerals, the bulk of tellurium extracted by industry is included in the composition of sulfides of other metals. In particular, tellurium, to a somewhat lesser extent than selenium, is part of the chalcopyrite of copper-nickel deposits of magmatic origin, as well as chalcopyrite developed in copper pyrite hydrothermal deposits. Tellurium is also found in the pyrite, chalcopyrite, molybdenite and galena deposits of porphyry copper ores, polymetallic deposits of the Altai type, galena of lead-zinc deposits associated with skarns, sulfide-cobalt, antimony-mercury and some others. The content of tellurium in molybdenite ranges from 8-53 g/t, in chalcopyrite 9-31 g/t, in pyrite - up to 70 g/t.

Receipt

Chemical properties

In chemical compounds, tellurium exhibits oxidation states -2; +2; +4; +6. It is an analogue of sulfur and selenium, but chemically less active than sulfur. It is soluble in alkalis, amenable to the action of nitric and sulfuric acids, but slightly soluble in dilute hydrochloric acid. Metallic tellurium begins to react with water at 100 °C.

It forms TeO, TeO 2, TeO 3 compounds with oxygen. In the form of a powder, it oxidizes in air even at room temperature, forming TeO 2 oxide. When heated in air, it burns out, forming TeO 2 - a strong compound with less volatility than tellurium itself. This property is used to purify tellurium from oxides, which are reduced by running hydrogen at a temperature of 500-600 °C. Tellurium dioxide is poorly soluble in water, well - in acidic and alkaline solutions.

In the molten state, tellurium is rather inert; therefore, graphite and quartz are used as container materials for its melting.

Tellurium forms a compound with hydrogen when heated, easily reacts with halogens, interacts with sulfur, phosphorus and metals. When reacted with concentrated sulfuric acid, it forms sulfite. Forms weak acids: telluric (H 2 Te), telluric (H 2 TeO 3) and telluric (H 6 TeO 6), most of whose salts are poorly soluble in water.

isotopes

Application

Alloys

Tellurium is used in the production of lead alloys with increased ductility and strength (used, for example, in the manufacture of cables). With the introduction of 0.05% tellurium, the loss of lead for dissolution under the influence of sulfuric acid is reduced by 10 times, and this is used in the production of lead-acid batteries. It is also important that tellurium-doped lead does not weaken during plastic deformation, and this makes it possible to carry out the technology of manufacturing current collectors of battery plates by cold die cutting and significantly increase the service life and specific characteristics of the battery.

As part of the alloy CZT (cadmium-zinc telluride, CdZnTe) is used in the manufacture of X-ray and gamma radiation detectors that operate at room temperature.

Thermoelectric materials

Its role is also great in the production of semiconductor materials and, in particular, tellurides of lead, bismuth, antimony, cesium. In the coming years, the production of lanthanide tellurides, their alloys and alloys with metal selenides for the production of thermoelectric generators with a very high (up to 72-78%) efficiency will become very important, which will make it possible to use them in the energy sector and in the automotive industry.

So, for example, a very high thermo-EMF was recently discovered in manganese telluride (500 μV / K) and in its combination with bismuth, antimony and lanthanide selenides, which allows not only to achieve a very high efficiency in thermogenerators, but also to implement in one stage semiconductor refrigerator cooling down to the cryogenic region (temperature level liquid nitrogen) temperatures and even lower. The best tellurium-based material for the production of semiconductor refrigerators in last years was an alloy of tellurium, bismuth and cesium, which made it possible to obtain a record cooling down to -237 ° C. At the same time, as a thermoelectric material, a tellurium-selenium alloy (70% selenium) is promising, which has a thermo-EMF coefficient of about 1200 μV/K.

Narrow gap semiconductors

KRT alloys (cadmium - tellurium) have also received absolutely exceptional importance, which have fantastic characteristics for detecting radiation from rocket launches and observing the enemy from space through atmospheric windows (cloudiness does not matter). MCT is one of the most expensive materials in the modern electronics industry.

High temperature superconductivity

A number of systems containing tellurium have recently discovered the existence of three (possibly four) phases in them, in which superconductivity does not disappear at a temperature slightly above the boiling point of liquid nitrogen.

Rubber production

A separate area of ​​application for tellurium is its use in the rubber vulcanization process.

Production of chalcogenide glasses

Tellurium is used in the melting of special grades of glass (where it is used in the form of dioxide), special glasses doped with rare earth metals are used as active bodies in optical quantum generators.

In addition, some tellurium-based glasses are semiconductors, a property that finds application in electronics.

Special grades of tellurium glass (the advantage of such glasses is transparency, fusibility and electrical conductivity) are used in the design of special chemical equipment (reactors).

Tellurium finds limited use for the production of lamps with its pairs - they have a spectrum very close to the sun.

CD-RW

Tellurium alloy is used in rewritable compact discs (particularly by Mitsubishi Chemical Corporation brand "Verbatim") to create a deformable reflective layer.

Biological role

Physiological action

Tellurium and its volatile compounds are toxic. Ingestion causes nausea, bronchitis, pneumonia. MPC in the air fluctuates for various compounds 0.007-0.01 mg / m³, in water 0.001-0.01 mg / l. Tellurium has not been confirmed to be carcinogenic.

In case of poisoning, tellurium is excreted from the body in the form of disgustingly smelling volatile organotellurium compounds - alkyl tellurides, mainly dimethyl telluride (CH 3) 2 Te. Their smell resembles the smell of garlic, therefore, when even small amounts of tellurium enter the body, the air exhaled by a person acquires this smell, which is an important symptom of tellurium poisoning.

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Notes

1. Michael E. Wieser, Norman Holden, Tyler B. Coplen, John K. Böhlke, Michael Berglund, Willi A. Brand, Paul De Bièvre, Manfred Gröning, Robert D. Loss, Juris Meija, Takafumi Hirata, Thomas Prohaska, Ronny Schoenberg, Glenda O'Connor, Thomas Walczyk, Shige Yoneda, Xiang‑Kun Zhu.(English) // Pure and Applied Chemistry. - 2013. - Vol. 85, no. 5 . - P. 1047-1078. - DOI:10.1351/PAC-REP-13-03-02 .
2. (English) . WebElements. Retrieved 5 August 2010.
3. Leddicote, G. W. (1961), , Nuclear science series, Subcommittee on Radiochemistry, National Academy of Sciences-National Research Council, p. 5 ,
4. Editorial staff: Zefirov N. S. (editor-in-chief). Chemical Encyclopedia: in 5 volumes. - Moscow: Soviet Encyclopedia, 1995. - T. 4. - S. 514. - 639 p. - 20,000 copies. - ISBN 5-85270-039-8.
6. Glinka N. L. General chemistry. - M .: "Chemistry", 1977, revised. - S. 395. - 720 p.
7. Tellurium- article from the Great Soviet Encyclopedia
8. G. Audi, O. Bersillon, J. Blachot and A. H. Wapstra (2003). "". Nuclear Physics A 729 : 3–128. DOI:10.1016/j.nuclphysa.2003.11.001 . Bibcode :.
9. The tellurium-123 isotope was considered radioactive (β − -active with a half-life of 6·10 14 years), but after additional measurements it was found to be stable within the sensitivity of the experiment.
10. 2.2 quadrillion years - on the long scale.
11. . International Program on Chemical Safety (January 28, 1998). Retrieved January 12, 2007. .
12. Wright, P.L. (1966). "". AJP-Legacy 211 (1): 6–10. PMID 5911055.
13. (1989) "Tellurium-intoxication". Klinische Wochenschrift 67 (22): 1152–5. DOI:10.1007/BF01726117. PMID 2586020.
14. Taylor, Andrew (1996). Biochemistry of tellurium. Biological Trace Element Research 55 (3): 231–239. DOI:10.1007/BF02785282. PMID 9096851.

Links

Periodic system of chemical elements of D. I. Mendeleev
																														Te
																							alkaline earth metals

An excerpt characterizing Tellurus

In the evening, Napoleon, between two orders - one to deliver the prepared fake Russian banknotes for import to Russia as soon as possible, and the other to shoot a Saxon, in whose intercepted letter information about orders for the French army was found - made a third order - about the reckoning of the Polish colonel who threw himself needlessly into the river to the cohort of honor (Legion d "honneur), of which Napoleon was the head.
Qnos vult perdere - dementat. [Whom wants to destroy - deprive of reason (lat.)]

Meanwhile, the Russian emperor had already been living in Vilna for more than a month, making reviews and maneuvers. Nothing was ready for the war, which everyone expected and in preparation for which the emperor had come from Petersburg. There was no general plan of action. The hesitations as to which plan, of all those proposed, should be adopted, only increased even more after the emperor's month-long stay in the main apartment. In the three armies there was a separate commander-in-chief in each, but there was no common commander over all the armies, and the emperor did not assume this title.
The longer the emperor lived in Vilna, the less and less they prepared for war, tired of waiting for it. All the aspirations of the people surrounding the sovereign, it seemed, were aimed only at making the sovereign, while having a good time, forget about the upcoming war.
After many balls and holidays with the Polish magnates, with the courtiers and with the sovereign himself, in the month of June, one of the Polish adjutant generals of the sovereign had the idea to give dinner and a ball to the sovereign on behalf of his adjutant generals. This idea was welcomed by all. The Emperor agreed. The adjutant general collected money by subscription. The person who could be most pleasing to the sovereign was invited to be the hostess of the ball. Count Benigsen, a landowner in the Vilna province, offered his country house for this holiday, and on June 13 a dinner, a ball, boating and fireworks were scheduled at Zakret, Count Benigsen's country house.
On the very day on which Napoleon gave the order to cross the Neman and his advanced troops, pushing back the Cossacks, crossed the Russian border, Alexander spent the evening at Benigsen's dacha - at a ball given by the general's adjutants.
It was a cheerful, brilliant holiday; experts in the business said that so many beauties rarely gathered in one place. Countess Bezukhova, among other Russian ladies who came for the sovereign from St. Petersburg to Vilna, was at this ball, obscuring the sophisticated Polish ladies with her heavy, so-called Russian beauty. She was noticed, and the sovereign honored her with a dance.
Boris Drubetskoy, en garcon (a bachelor), as he said, having left his wife in Moscow, was also at this ball and, although not an adjutant general, was a large participant in the subscription for the ball. Boris was now a wealthy man who had gone far in honors, no longer seeking patronage, but standing on an even footing with the highest of his peers.
At twelve o'clock in the morning they were still dancing. Helen, who did not have a worthy gentleman, herself offered the mazurka to Boris. They sat in the third pair. Boris, coolly looking at Helen's shiny bare shoulders, protruding from a dark gauze dress with gold, talked about old acquaintances and at the same time, imperceptibly to himself and others, did not stop watching the sovereign for a second, who was in the same hall. The sovereign did not dance; he stood at the door and stopped one or the other with those kind words that he alone knew how to utter.
At the beginning of the mazurka, Boris saw that Adjutant General Balashev, one of the closest persons to the sovereign, approached him and stopped courtly close to the sovereign, who was talking to a Polish lady. After talking with the lady, the emperor looked inquiringly and, apparently realizing that Balashev did this only because there were important reasons for this, nodded slightly to the lady and turned to Balashev. Balashev had just begun to speak, as surprise was expressed on the sovereign's face. He took Balashev's arm and walked with him through the hall, unconsciously clearing sazhens on both sides of the three broad roads that stood aside before him. Boris noticed the agitated face of Arakcheev, while the sovereign went with Balashev. Arakcheev, looking frowningly at the sovereign and sniffing his red nose, moved out of the crowd, as if expecting the sovereign to turn to him. (Boris realized that Arakcheev was jealous of Balashev and was dissatisfied with the fact that some, obviously important, news was not transmitted to the sovereign through him.)
But the sovereign with Balashev passed, without noticing Arakcheev, through the exit door into the illuminated garden. Arakcheev, holding his sword and looking around angrily, walked twenty paces behind them.
As long as Boris continued to make the figures of the mazurka, he never ceased to be tormented by the thought of what kind of news Balashev brought and how to find out before others.
In the figure where he had to choose the ladies, whispering to Helen that he wanted to take Countess Pototskaya, who, it seems, went out onto the balcony, he, sliding his feet on the parquet, ran out the exit door into the garden and, noticing the sovereign entering with Balashev on the terrace , paused. The Emperor and Balashev were heading for the door. Boris, in a hurry, as if not having time to move away, respectfully pressed himself against the lintel and bent his head.
The sovereign, with the excitement of a personally offended person, finished the following words:
- Without declaring war, enter Russia. I will make peace only when not a single armed enemy remains on my land,” he said. As it seemed to Boris, it was pleasant for the sovereign to express these words: he was pleased with the form of expression of his thoughts, but was dissatisfied with the fact that Boris heard them.
- so that no one knows anything! added the sovereign, frowning. Boris realized that this was referring to him, and, closing his eyes, tilted his head slightly. The emperor again entered the hall and stayed at the ball for about half an hour.
Boris was the first to learn the news of the crossing of the Neman by the French troops, and thanks to this, he had the opportunity to show some important people that he knew a lot that was hidden from others, and through this he had the opportunity to rise higher in the opinion of these persons.

The unexpected news that the French had crossed the Neman was especially unexpected after a month of unfulfilled expectations, and at the ball! The emperor, in the first minute of receiving the news, under the influence of indignation and insult, found that, which later became famous, a saying that he himself liked and fully expressed his feelings. Returning home from the ball, at two in the morning the sovereign sent for Secretary Shishkov and ordered him to write an order to the troops and a rescript to Field Marshal Prince Saltykov, in which he certainly demanded that the words be placed that he would not reconcile until at least one an armed Frenchman will remain on Russian soil.
The next day the following letter was written to Napoleon.
Monsieur mon frere. J "ai appris hier que malgre la loyaute avec laquelle j" ai maintenu mes engagements envers Votre Majeste, ses troupes ont franchis les frontieres de la Russie, et je recois a l "instant de Petersbourg une note par laquelle le comte Lauriston, pour cause de cette agression, annonce que votre majeste s "est consideree comme en etat de guerre avec moi des le moment ou le prince Kourakine a fait la demande de ses passeports. Les motifs sur lesquels le duc de Bassano fondait son refus de les lui delivrer, n "auraient jamais pu me faire supposer que cette demarche servirait jamais de pretexte a l" agression. En effet cet ambassadeur n "y a jamais ete autorise comme il l" a declare lui meme, et aussitot que j "en fus informe, je lui ai fait connaitre combien je le desapprouvais en lui donnant l" ordre de rester a son poste. Si Votre Majeste n "est pas intentionnee de verser le sang de nos peuples pour un malentendu de ce genre et qu" elle consente a retirer ses troupes du territoire russe, je regarderai ce qui s "est passe comme non avenu, et un accommodement entre nous sera possible. Dans le cas contraire, Votre Majeste, je me verrai force de repousser une attaque que rien n "a provoquee de ma part. Il depend encore de Votre Majeste d "eviter a l" humanite les calamites d "une nouvelle guerre.
Je suis, etc.
(signe) Alexandre.
[“My lord brother! Yesterday it dawned on me that, despite the frankness with which I observed my obligations in relation to Your Imperial Majesty, Your troops crossed the Russian borders, and only now received a note from Petersburg, which Count Lauriston informs me about this invasion, that Your Majesty considers yourself in hostile relations with me since the time when Prince Kurakin demanded his passports. The reasons on which the Duke of Bassano based his refusal to issue these passports could never have led me to suppose that my ambassador's act was the occasion for the attack. And in fact, he had no order from me to do so, as he himself announced; and as soon as I found out about this, I immediately expressed my displeasure to Prince Kurakin, ordering him to fulfill the duties entrusted to him as before. If Your Majesty is not disposed to shed the blood of our subjects because of such a misunderstanding, and if you agree to withdraw your troops from the Russian possessions, then I will ignore everything that has happened, and an agreement between us will be possible. Otherwise, I will be forced to repel an attack that was not initiated by anything on my part. Your Majesty, you still have the opportunity to save humanity from the scourge of a new war.
(signed) Alexander. ]

On June 13, at two o'clock in the morning, the sovereign, having called Balashev to him and read his letter to Napoleon to him, ordered him to take this letter and personally hand it over to the French emperor. Sending Balashev, the sovereign again repeated to him the words that he would not reconcile until at least one armed enemy remained on Russian soil, and ordered that these words be conveyed to Napoleon without fail. The sovereign did not write these words in the letter, because he felt with his tact that these words were inconvenient to convey at the moment when the last attempt at reconciliation was being made; but he certainly ordered Balashev to hand them over to Napoleon personally.
Leaving on the night of June 13-14, Balashev, accompanied by a trumpeter and two Cossacks, arrived at dawn in the village of Rykonty, at the French outposts on this side of the Neman. He was stopped by French cavalry sentries.
A French hussar non-commissioned officer, in a crimson uniform and a shaggy hat, shouted at Balashev, who was approaching, ordering him to stop. Balashev did not immediately stop, but continued to move along the road at a pace.
The non-commissioned officer, frowning and muttering some kind of curse, advanced with his horse's chest on Balashev, took up his saber and rudely shouted at the Russian general, asking him: is he deaf that he does not hear what they say to him. Balashev named himself. The non-commissioned officer sent a soldier to the officer.
Paying no attention to Balashev, the non-commissioned officer began to talk with his comrades about his regimental affairs and did not look at the Russian general.
It was extraordinarily strange for Balashev, after being close to the highest power and might, after a conversation three hours ago with the sovereign and generally accustomed to honors in his service, to see here, on Russian soil, this hostile and, most importantly, disrespectful attitude of brute force towards himself.
The sun was just beginning to rise from behind the clouds; the air was fresh and dewy. On the way, the herd was driven out of the village. In the fields, one by one, like bubbles in water, the larks burst up with a chuckle.
Balashev looked around him, waiting for the arrival of an officer from the village. The Russian Cossacks, and the trumpeter, and the French hussars silently looked at each other from time to time.
A French hussar colonel, apparently just out of bed, rode out of the village on a handsome, well-fed gray horse, accompanied by two hussars. On the officer, on the soldiers and on their horses there was a look of contentment and panache.
This was the first time of the campaign, when the troops were still in good order, almost equal to a lookout, peaceful activity, only with a touch of elegant militancy in dress and with a moral touch of that fun and enterprise that always accompany the beginning of campaigns.
The French colonel could hardly hold back a yawn, but he was courteous and, apparently, understood the full significance of Balashev. He led him past his soldiers by the chain and informed him that his desire to be presented to the emperor would probably be immediately fulfilled, since the imperial apartment, as far as he knew, was not far away.
They passed the village of Rykonty, past the French hussar hitching posts, sentries and soldiers saluting their colonel and examining the Russian uniform with curiosity, and drove to the other side of the village. According to the colonel, the head of the division was two kilometers away, who would receive Balashev and escort him to his destination.
The sun had already risen and shone cheerfully on the bright greenery.
They had just left behind the tavern on the mountain, when a group of horsemen appeared to meet them from under the mountain, in front of which, on a black horse with a harness shining in the sun, rode a tall man in a hat with feathers and black hair curled to the shoulders, in a red mantle and with long legs sticking out forward, as the French ride. This man galloped towards Balashev, shining and fluttering in the bright June sun with his feathers, stones and gold galloons.
Balashev was already at a distance of two horses from the rider galloping towards him with a solemnly theatrical face in bracelets, feathers, necklaces and gold, when Yulner, a French colonel, respectfully whispered: "Le roi de Naples." [King of Naples.] Indeed, it was Murat, now called the Neapolitan king. Although it was completely incomprehensible why he was a Neapolitan king, he was called that, and he himself was convinced of this and therefore had a more solemn and important air than before. He was so sure that he was really the Neapolitan king that, on the eve of his departure from Naples, during his walk with his wife through the streets of Naples, several Italians shouted to him: “Viva il re!”, [Long live the king! (Italian)] he turned to his wife with a sad smile and said: “Les malheureux, ils ne savent pas que je les quitte demain! [Unfortunate, they don't know that I'm leaving them tomorrow!]
But despite the fact that he firmly believed that he was a Neapolitan king, and that he regretted the sorrow of his subjects who were leaving him, in recent times, after he was ordered to enter the service again, and especially after a meeting with Napoleon in Danzig, when the august brother-in-law said to him: “Je vous ai fait Roi pour regner a maniere, mais pas a la votre”, [I made you king in order to reign not according to my own, but according to mine.] - he cheerfully began for a business familiar to him and, like a horse that was fried, but not fat, fit for service, sensing himself in a harness, played in the shafts and, discharged as colorfully and expensively as possible, cheerful and contented, galloped, not knowing where and why, along the roads Poland.

Tellurium(lat. Tellurium), Te, a chemical element of group VI of the main subgroup of Mendeleev's periodic system; atomic number 52, atomic mass 127.60, refers to rare trace elements. It occurs in nature in the form of eight stable isotopes with mass numbers 120, 122-126, 128, 130, of which 128 Te (31.79%) and 130 Te (34.48%) are the most common. Of the artificially obtained radioactive isotopes, 127 Te (T ½ = 105 days) and 129 Te (T ½ = 33.5 days) are widely used as labeled atoms. Tellurium was discovered by F. Müller in 1782. The German scientist M. G. Klaproth confirmed this discovery and gave the element the name "tellurium" (from the Latin tellus, genus telluris - Earth). The first systematic studies of the chemistry of Tellurium were carried out in the 30s of the 19th century by I. Ya. Berzelius.

Distribution of Tellurium in nature. Tellurium is one of the rarest elements; average content in the earth's crust (clarke) ~1·10 -7% by weight. Tellurium is dispersed in magma and biosphere; from some hot underground sources is deposited together with S, Ag, Au, Pb and other elements. Hydrothermal deposits of Au and non-ferrous metals enriched in Tellurium are known; about 40 minerals of this element are associated with them (the most important are altaite, tellurobismuthite and other natural tellurides). An admixture of Tellurium in pyrite and other sulfides is characteristic. Tellurium is extracted from polymetallic ores.

Physical properties of Tellurium. Tellurium is silvery-white in color with a metallic luster, brittle, becomes plastic when heated. Crystallizes in the hexagonal system: a = 4.4570Å; c = 5.9290Å; density 6.25 g / cm 3 at 20 "C; t pl 450 ° C; t kip 990 ° C; specific heat at 20 ° C 0.204 kJ / (kg K); thermal conductivity at 20 ° C 5.999 W / (m K); temperature coefficient of linear expansion 1.68 10 -5 (20 ° C). Tellurium is diamagnetic, specific magnetic susceptibility at 18 ° C -0.31 10 -6. Brinell hardness 184.3 MN / m 2 (18.43 kgf / mm 2) Atomic radius 1.7 Å, ionic radii: Te 2- 2.22 Å, Te 4+ 0.89 Å, Te 6+ 0.56 Å.

Tellurium is a semiconductor. Band gap 0.34 eV. Under normal conditions and up to the melting point, pure Tellurium has a p-type conductivity. With a decrease in temperature in the range (-100 °C) - (-80 °C), a transition occurs: the conductivity of Tellurium becomes n-type. The temperature of this transition depends on the purity of the sample, and it is lower, the purer the sample.

Chemical properties of Tellurium. The configuration of the outer electron shell of the atom Te 5s 2 5p 4 . In compounds, it exhibits oxidation states -2; +4; + 6, rarely +2. Tellurium is a chemical analogue of sulfur and selenium with more pronounced metallic properties. With oxygen, Tellurium forms oxide (II) TeO, oxide (IV) TeO 2 and oxide (VI) TeO 3. TeO exists above 1000°C in the gas phase. TeO 2 is obtained by burning Te in air, has amphoteric properties, is difficult to dissolve in water, but is easily soluble in acidic and alkaline solutions. TeO 3 is unstable, can only be obtained by decomposition of telluric acid. When heated, Tellurium reacts with hydrogen to form hydrogen telluride H 2 Te, a colorless poisonous gas with a sharp, unpleasant odor. Reacts easily with halogens; it is characterized by halides such as TeX 2 and TeX 4 (where X is Cl and Br); also received TeF 4 , TeF 6 ; they are all highly volatile and are hydrolyzed by water. Tellurium directly interacts with non-metals (S, P), as well as with metals; it reacts at room temperature with concentrated nitric and sulfuric acids, in the latter case TeSO 3 is formed, which is oxidized when heated to TeOSO 4 . Relatively weak Te acids are known: hydrogen telluric (solution of H 2 Te in water), telluric H 2 TeO 3 and telluric H 6 TeO 6; their salts (respectively tellurides, tellurites and tellurates) are slightly or completely insoluble in water (with the exception of alkali metal and ammonium salts). Some organic derivatives of Tellurium are known, for example RTeH, dialkyltellurides R 2 Te - low-boiling liquids with an unpleasant odor.

Getting Tellurium. Tellurium is extracted incidentally during the processing of sulfide ores from semi-products of copper, lead and zinc production, as well as from some gold ores. The main source of raw materials for the production of Tellurium is copper electrolysis sludge containing from 0.5 to 2% Te, as well as Ag, Au, Se, Cu and other elements. The sludge is first freed from Cu, Se, the residue containing noble metals, Te, Pb, Sb and other components is melted down to obtain an alloy of gold and silver. Tellurium in the form of Na 2 TeO 3 passes into soda-tellurium slags, where its content reaches 20-35%. The slag is crushed, ground and leached with water. Tellurium is deposited from solution by electrolysis at the cathode. The resulting tellurium concentrate is treated with alkali in the presence of aluminum powder, converting Tellurium into a solution in the form of tellurides. The solution is separated from the insoluble residue, concentrating impurities heavy metals, and blown with air. In this case, Tellurium (purity 99%) is deposited in the elemental state. High-purity tellurium is obtained by repeating telluride processing. The purest Tellurium is obtained by a combination of chemical purification, distillation, and zone melting methods.

Tellurium application. Tellurium is used in semiconductor technology; as an alloying additive - in lead alloys, cast iron and steel to improve their machinability and improve mechanical characteristics; Bi 2 Te 3 and Sb 2 Te 3 are used in thermogenerators, and CdTe is used in solar batteries and as semiconductor laser materials. Tellurium is also used for bleaching cast iron, vulcanizing latex mixtures, and producing brown and red glasses and enamels.

Tellurium in the body. Tellurium is constantly present in the tissues of plants and animals. In plants growing on soils rich in Tellurium, its concentration reaches 2·10 -4 - 2.5·10 -3%, in terrestrial animals - about 2·10 -6%. In humans, the daily intake of Tellurium with food and water is about 0.6 mg; It is excreted from the body mainly with urine (over 80%), as well as with feces. Moderately toxic to plants and highly toxic to mammals (causes growth retardation, hair loss, paralysis, etc.).

Professional poisoning of Tellurium is possible during its smelting and other production operations. Chills, headache, weakness, rapid pulse, lack of appetite, metallic taste in the mouth, garlic smell of exhaled air, nausea, dark coloration of the tongue, irritation of the respiratory tract, sweating, hair loss are observed.

Discovered by F. Müller in 1782. The name of the element comes from the Latin tellus, the genitive telluris, Earth (the name was proposed by M. G. Klaproth, who singled out the element as a simple substance and determined its most important properties).

Receipt:

It exists in nature as a mixture of 8 stable isotopes (120, 122-126, 128, 130). The content in the earth's crust is 10 -7%. The main minerals - altaite (PbTe), tellurobismuthite (Bi 2 Te 3), tetradymite (Bi 2 Te 2 S), are found in many sulfide ores.
It is obtained from copper production sludge by leaching with a NaOH solution in the form of Na 2 TeO 3 , from which tellurium is released electrolytically. Further purification - sublimation and zone melting.

Physical properties:

Compact tellurium is a silvery-gray substance with a metallic luster, having a hexagonal crystal lattice (density 6.24 g/cm 3 , melting point - 450°C, boiling point - 990°C). It precipitates from solutions in the form of a brown powder, in vapors it consists of Te 2 molecules.

Chemical properties:

Tellurium is stable in air at room temperature and reacts with oxygen when heated. Reacts with halogens, reacts with many metals when heated.
When heated, tellurium is oxidized by water vapor to form tellurium(II) oxide and reacts with concentrated sulfuric and nitric acids. When boiling in aqueous solutions of alkalis, it disproportionates similarly to sulfur:
8 Te + 6NaOH \u003d Na 2 TeO 3 + 2Na 2 Te + 3H 2 O
In compounds, it exhibits oxidation states -2, +4, +6, less often +2.

The most important connections:

Tellurium(IV) oxide, tellurium dioxide, TeO 2 , poorly soluble in water, acidic oxide, reacts with alkalis, forming salts of tellurous acid. It is used in laser technology, a component of optical glasses.
Tellurium(VI) oxide, tellurium trioxide, TeO 3 , yellow or gray substance, practically insoluble in water, decomposes when heated to form dioxide, reacts with alkalis. Obtained by decomposition of telluric acid.
Tellurous acid, H 2 TeO 3 , slightly soluble, prone to polymerization, therefore, it usually represents a precipitate with a variable water content TeO 2 * nH 2 O. Salts - tellurites(M 2 TeO 3) and polytellurites (M 2 Te 2 O 5, etc.), usually obtained by sintering carbonates with TeO 2, are used as components of optical glasses.
Telluric acid, H 6 TeO 6 , white crystals, soluble in hot water. A very weak acid, in solution it forms salts of the composition MH 5 TeO 6 and M 2 H 4 TeO 6 . When heated in a sealed ampoule, metatelluric acid H 2 TeO 4 was also obtained, which gradually turns into telluric acid in solution. Salts - tellurates. It is also obtained by fusing tellurium (IV) oxide with alkalis in the presence of oxidizing agents, fusing telluric acid with a carbonate or metal oxide. Alkali metal tellurates are soluble. They are used as ferroelectrics, ion exchangers, components of luminescent compositions.
Telluride hydrogen, H 2 Te - a poisonous gas with an unpleasant odor, obtained by hydrolysis of aluminum telluride. A strong reducing agent, in solution it is rapidly oxidized by oxygen to tellurium. In an aqueous solution, an acid is stronger than sulfur and hydroselenic acid. Salts - tellurides, usually obtained by the interaction of simple substances, alkali metal tellurides are soluble. Many p- and d-element tellurides are semiconductors.
Halides. Tellurium(II) halides are known, for example TeCl 2 , salt-like, when heated and in solution disproportionate to Te and Te(IV) compounds. Tellurium tetrahalides are solids, hydrolyze in solution to form tellurous acid, easily form complex halides (for example, K 2 ). TeF 6 hexafluoride, a colorless gas, unlike sulfur hexafluoride, is easily hydrolyzed to form telluric acid.

Application:

Component of semiconductor materials; alloying addition to cast iron, steels, lead alloys.
World production (without the USSR) - about 216 tons / year (1976).
Tellurium and its compounds are toxic. MPC is about 0.01 mg/m 3 .

See also:
Tellurium // Wikipedia. . Update date: 12/20/2017. URL: http://ru.wikipedia.org/?oldid=89757888 (date of access: 12/25/2017).
The discovery of the elements and the origin of their names. Tellurium //
URL: http://www.chem.msu.su/rus/history/element/Te.html