home Windows and doors Rubidium metal. Properties of rubidium. Application of rubidium. Oxidation state of rubidium Occurrence of rubidium in nature prevalence

Rubidium metal. Properties of rubidium. Application of rubidium. Oxidation state of rubidium Occurrence of rubidium in nature prevalence

Rubidium(lat. Rubidium), Rb, chemical element of group I of the periodic system of Mendeleev; atomic number 37, atomic mass 85.4678; silvery-white metal, belongs to the alkali metals. Natural Rubidium is a mixture of two isotopes: stable 85 Rb (72.15%) and weakly radioactive 87 Rb (half-life T ½ 4.8 10 10 years). The β decay of 87 Rb produces stable 87 Sr. Determining the content of 87 Sr and Rubidium in rocks and minerals (strontium method) makes it possible to reliably establish their geological age. About 20 radioactive isotopes of Rubidium have been artificially produced. Rubidium was discovered in 1861 by R. Bunsen and G. Kirchhoff during a spectral study of salts isolated from mineral waters. The name of the element is given by the color of the most characteristic red lines of the spectrum (from the Latin rubidus - red, dark red). Metallic rubidium was first obtained in 1863 by Bunsen.

Distribution of Rubidium in nature. Rubidium is a typical trace element. Despite the relatively high content in the earth's crust (clarke) of 1.5 10 -2% by mass, that is, more than that of Cu, Pb, Zn and many other metals, Rubidium does not form its own minerals and mainly enters as an isomorphic impurity in potassium and cesium minerals (sylvite, carnallite, microcline, Rb-muscovite, etc.). Rubidium, like potassium, is found in acidic igneous rocks (granitoids) and especially in pegmatites (up to 1-3% Rubidium). There is little rubidium in ultrabasic and basic rocks (2·10 -4 and 4.5·10 -3%, respectively). The waters of the seas and oceans contain from 1.0·10 -5 to 2.1·10 -5% Rubidium. Rubidium salts are part of the waters of many mineral springs.

The richest in Rubidium are the so-called concentrator minerals: lepidolite, zinnwaldite, pollucite. Deposits of lithium and potassium minerals containing Rubidium are available in the USSR, Czechoslovakia, Germany, Namibia, Zimbabwe and other countries. The cosmic abundance of Rubidium is 6.5 atoms per 10 6 silicon atoms.

Physical properties of Rubidium. Rubidium forms silvery-white soft crystals that have a metallic luster when freshly cut. Brinell hardness 0.2 Mn/m2 (0.02 kgf/mm2). The crystal lattice of Rubidium is cubic body-centered, a = 5.70 Å (0 ° C). Atomic radius 2.48 Å, Rb ion radius + 1.49 Å. Density 1.525 g/cm 3 (0 °C), melting point 38.9 °C, boiling point 703 °C. Specific heat capacity 335.2 J/(kg K), thermal coefficient of linear expansion 9.0·10 -5 deg -1 (0-38 °C), elastic modulus 2.4 Gn/m 2 (240 kgf/mm 2 ), specific volumetric electrical resistance 11.29·10 -6 ohm·cm (20 °C); Rubidium is paramagnetic.

Chemical properties of Rubidium. The Rb atom easily donates a single electron from the outer shell (its configuration is 5s 1). Electronegativity Rubidium 0.89, first ionization potential 4.176 eV. In all chemical compounds, Rubidium is monovalent (oxidation state +1). The chemical activity of Rubidium is very high. It combines violently with oxygen, giving Rb 2 O 2 peroxide and RbO 2 superoxide (with a lack of oxygen, Rb 2 O oxide is formed). Rubidium reacts explosively with water, releasing hydrogen and forming a solution of Rubidium hydroxide, RbOH. The properties of RbOH are very similar to potassium hydroxide KOH. Rubidium combines directly with many nonmetals; reacts violently with most acids. Almost all rubidium salts are highly soluble in water. Perchlorate RbClO 4, chloroplatinate Rb 2 and some others are slightly soluble; they are used for the analytical determination of Rb along with the flame photometry method, based on the property of Rb vapor and its compounds to color the flame bright red.

Obtaining Rubidium. Rb salts are obtained as a by-product in the production of Li, Mg and K salts. Rubidium metal is obtained by reduction of RbCl in vacuum at 700-800 °C with calcium. Due to its high reactivity, Rubidium is stored in metal vessels under a layer of paraffin oil or in sealed glass ampoules in an inert atmosphere.

Application of Rubidium. Rubidium is used mainly in the production of cathodes for solar cells; They are also added to gas-discharge argon and neon tubes to enhance the intensity of the glow. Sometimes rubidium is introduced into special alloys (getters). Rubidium salts are used as catalysts in organic synthesis.

Rubidium in the body. Rubidium is constantly present in the tissues of plants and animals. Land plants contain about 0.00064% Rubidium, aquatic plants contain 2 times less. Rubidium accumulates in plants, as well as in the muscles and soft tissues of sea anemones, worms, mollusks, crustaceans, echinoderms and fish (accumulation coefficient 8-26). The highest accumulation coefficient (2600) of the artificial radioactive isotope 86 Rb is in the duckweed Lemna polyrrhiza, and among freshwater invertebrates in the mollusk Galba palustris - 370. The ash of the pectoral muscles of birds contains 0.0112-0.0135%. The metabolism of Rubidium in the body has been poorly studied.

Rubidium – (Rubidium) Rb, a chemical element of the 1st (Ia) group of the Periodic table. Alkaline element. Atomic number 37, relative atomic mass 85.4678. It occurs in nature as a mixture of the stable isotope 85 Rb (72.15%) and the radioactive isotope 87 Rb (27.86%) with a half-life of 4.8. 10 10 years. Another 26 radioactive isotopes of rubidium with mass numbers from 75 to 102 and half-lives from 37 ms (rubidium-102) to 86 days (rubidium-83) have been artificially obtained.

Atomic number - 37

Atomic mass - 85.468

Density, kg/m³ - 1530

Melting point, °C - 38.9

Heat capacity, kJ/(kg °C) - 0.335

Electronegativity - 0.8

Covalent radius, Å - 2.16

1st ionization potential, eV - 4.18

Oxidation state +1.

Rubidium was discovered in 1861 by German scientists Robert Bunsen and Gustav Kirchhoff and became one of the first elements discovered by spectroscopy, which was invented by Bunsen and Kirchhoff in 1859. Robert Bunsen and Gustav Kirchhoff mined 150 kg of lepidolite and obtained several grams of rubidium salts for analysis, thus they discovered a new element. The name of an element reflects the color of the brightest line in its spectrum.

Distribution of rubidium in nature

Rubidium is a typical trace element. Despite the relatively high content in the earth's crust (clarke) of 1.5 10 -2% by mass, that is, more than that of Cu, Pb, Zn and many other metals, Rubidium does not form its own minerals and mainly enters as an isomorphic impurity in potassium and cesium minerals (sylvite, carnallite, microcline, Rb-muscovite, etc.). Rubidium, like potassium, is found in acidic igneous rocks (granitoids) and especially in pegmatites (up to 1-3% Rubidium). There is little rubidium in ultrabasic and basic rocks (2·10 -4 and 4.5·10 -3%, respectively). The waters of the seas and oceans contain from 1.0·10 -5 to 2.1·10 -5% Rubidium. Rubidium salts are part of the waters of many mineral springs.

The richest in Rubidium are the so-called concentrator minerals: lepidolite, zinnwaldite, pollucite.

Rubidium deposits in Russia

For cesium and rubidium, pegmatites still remain the only raw material source of industrial importance. Pegmatite tin deposits are known in Eastern Siberia of Russia and are located in Precambrian complexes. The ores are usually complex, mined for tin, tantalum, niobium, scandium, rubidium, and partly for tungsten and bismuth.

The pollucite ores of the Vasin-Mylk deposit, located in the Lovozero region, contain large reserves of rubidium and cesium. The most important and largest source of rubidium, cesium, strontium and rare earths are the Khibiny apatite-nepheline ores.

Lepidolite is a mica group mineral that is a secondary source of lithium. It is one of the main sources of rare alkali metals, rubidium and cesium.

The state balance takes into account the Verkhnekamskoye deposit of potassium-magnesium salts, in which rubidium is an associated mineral. In salts, rubidium is associated with the carnallite sequence. The content of rubidium oxide in ores ranges from 0 to 120 g/t, the average is 90 g/t. The mass fraction of rubidium in the ore and enriched carnallite is 0.0104% and 0.013%, respectively. Balance sheet reserves of rubidium oxide (Rb2O) VKMKS are taken into account for the Palashersky and Remaining Area areas, off-balance reserves - for the Ust-Yaivinsky area.

The balance reserves of rubidium contained in the carnallite ores of the Bereznikovsky, Bygelsko-Troitsky, Solikamsky and Novo-Solikamsky areas have lost their industrial significance and have been written off. The reason for the write-off was the economic infeasibility of extracting rubidium. Rubidium reserves are not being developed due to the availability of more efficient raw material sources (pollucite concentrates), the processing technology of which is more profitable.

World reserves of rubidium

The content of rubidium in the earth's crust is 7.8·10−3%. This is approximately equal to the content of nickel, copper and zinc. In terms of abundance in the earth's crust, rubidium is approximately in 20th place, but in nature it is in a dispersed state, rubidium is a typical trace element. The intrinsic minerals of rubidium are unknown. Rubidium is found together with other alkaline elements and always accompanies potassium. It is found in many rocks and minerals, particularly in North America, South Africa and Russia, but its concentration there is extremely low. Only lepidolites contain slightly more rubidium, sometimes 0.2%, and occasionally up to 1-3% (in terms of Rb 2 O).

Rubidium salts are dissolved in the water of seas, oceans and lakes. Their concentration here is very low, on average about 100 µg/l. In some cases, the content of rubidium in water is higher: in the Odessa estuaries it turned out to be 670 μg/l, and in the Caspian Sea - 5700 μg/l. Increased rubidium content has also been found in some mineral springs in Brazil.

From seawater, rubidium passed into potassium salt deposits, mainly into carnallites. In the Strassfurt and Solikamsk carnallites, the rubidium content ranges from 0.037 to 0.15%. The mineral carnallite is a complex chemical compound formed by potassium and magnesium chlorides with water; its formula is KCl MgCl 2 6H 2 O. Rubidium gives a salt of similar composition RbCl MgCl 2 6H 2 O, and both salts - potassium and rubidium - have the same structure and form a continuous series of solid solutions, crystallizing together. Carnallite is highly soluble in water, so opening the mineral is not difficult. Rational and economical methods for extracting rubidium from carnallite, along with other elements, have now been developed and described in the literature.

Obtaining rubidium

Not all isotopes can be produced in nuclear reactors using nuclear reactions involving neutrons. Many radionuclides are synthesized in proton and heavy ion accelerators, for example, in cyclotrons. A complex for the production of radioactive isotopes of iodine-123, fluorine-18, carbon-11, nitrogen-13, oxygen-15, rubidium-81, gallium-67, indium-111, thallium-201 and radiopharmaceuticals (RP) on their basis.

As you know, the Kola Peninsula is rich in deposits of rare metals. In particular, the Voronyetundra deposit is located here - the most promising Russian deposit of the cesium mineral pollucite. In addition, the nepheline concentrate, mined together with apatite, contains a fairly high concentration of rubidium (about 0.014 wt.%). About 40 years ago, in connection with the planned use of rare alkali metals (primarily cesium) in ion rocket engines, the need arose to develop technology and organize industrial production of high-purity rubidium and cesium. On the initiative of Academician I.V. Tananaev, the necessary research was carried out at the Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials of the Kola Branch of the Academy of Sciences.

In principle, two strategies for obtaining high-purity metals are possible:

Obtaining high-purity compounds from various types of natural raw materials and their further processing into high-purity metals;

Obtaining rough metals (alloys) with their subsequent separation into individual metals and their further purification.

Pollucite is a hydrated cesium aluminosilicate containing up to 36.77 and 0.72 wt. % cesium and rubidium, respectively. The zeolite structure of pollucite determines the presence of water in it, which cannot be completely removed even with long-term high-temperature (800-850o) vacuum calcination. Associated minerals, as a rule, are other aluminosilicates (primarily analcime), lepidolite, tantalite, and other minerals. Pollucite-containing ores often form large ore bodies that are easily enriched by manual disassembly to produce rich concentrates. The content of cesium oxide in them is ≥ 26, rubidium oxide up to 1.7 wt. % (the increased rubidium content is due to the presence of lepidolite in the concentrate). However, the main part of the Voronetundrovskoye and other deposits in Russia is characterized by finely disseminated ores, for which methods of mechanical and chemical enrichment have been developed. During chemical enrichment, cesium is recovered not in the form of pollucite, but in the form of salt concentrates. To process pollucite into chemical compounds, a number of technologies have been proposed that make it possible to obtain various compounds or concentrates based on them (nitrates, sulfates, chlorides, carbonates, etc.). The production of concentrates through chemical processing of raw materials is much cheaper than commercial salts.

Rubidium is a trace element. It is isolated in the form of chloride, nitrate, sulfate, and carbonate concentrates during the chemical processing of various types of mineral raw materials. In particular, methods have been developed for the production of rubidium carbonate concentrates from nepheline, rubidium chloride concentrates from carnallite, pilot production of which was carried out at the Volkhov Aluminum Plant, the Pikalevsky Alumina Refinery and the Berezniki Titanium-Magnesium Plant.

Cesium nitrate was obtained during the processing of pollucite at the Novosibirsk Chemical Reagents Plant, nitrate and carbonate concentrates of rubidium and cesium - incidentally during the processing of spodumene at the Krasnoyarsk Chemical and Metallurgical Plant.

Thermodynamic analysis of possible reactions showed that the processes are characterized by small values of change in the Gibbs energy, and, as a consequence, direct high extraction of target components cannot be obtained in them. However, it was achieved due to a shift in equilibrium, achieved by continuous distillation of a more easily boiling target component (rubidium, cesium) from the reaction zone. When reducing concentrates with a relatively low content of rubidium or cesium, the concentration of the target component in rough alloys could be significantly increased already at the reduction stage. Thus, when reducing potash concentrates containing about (wt.) 10.7% rubidium with sodium, the resulting rubidium-potassium alloy contained about 50% rubidium, and when reducing with potassium - over 60%.

Thermodynamic calculations have shown that the reduction of rubidium and cesium carbonates with sodium can proceed in parallel through two reactions:

(Rb, Cs)2CO3 + 2Na → 2(Rb, Cs) + Na2CO3 and

(Rb, Cs)2CO3 + 6Na → 2(Rb, Cs) + 3Na2O+C

This technology for producing high-purity rubidium and cesium hydroxides by reacting metals with high-purity water (protium or deuterated) made it possible to organize the production of many highly pure compounds, primarily phosphates and halides. Research has made it possible to create industrial production of high-purity rubidium and cesium from raw materials of the Kola Peninsula.

Applications of rubidium

Although rubidium is inferior to cesium in some applications, this rare alkali metal plays an important role in modern technology. The following main areas of application of rubidium can be noted: catalysis, electronics industry, special optics, nuclear industry, medicine.

Rubidium is used not only in its pure form, but also in the form of a number of alloys and chemical compounds. Rubidium has a good raw material base, more favorable than for cesium. The scope of rubidium is expanding due to its increasing availability.

The isotope rubidium-86 is widely used in gamma flaw detection, measurement technology, as well as in the sterilization of drugs and food products. Rubidium and its alloys with cesium are a very promising coolant and working medium for high-temperature turbine units (in this regard, rubidium and cesium have become important in recent years, and the extreme high cost of metals is taking a backseat to the possibilities of dramatically increasing the efficiency of turbine units, and therefore and reduce fuel consumption and environmental pollution). Rubidium-based systems most widely used as coolants are ternary alloys: sodium-potassium-rubidium, and sodium-rubidium-cesium.

In catalysis, rubidium is used in both organic and inorganic synthesis. The catalytic activity of rubidium is used mainly for the refining of petroleum into a number of important products. Rubidium acetate, for example, is used for the synthesis of methanol and a number of higher alcohols from water gas, which is important in connection with the underground gasification of coal and in the production of artificial liquid fuels for cars and jet fuel. A number of alloys of rubidium with tellurium have higher sensitivity in the ultraviolet region of the spectrum than cesium compounds, and therefore, in this case, it is able to compete with cesium as a material for photoconverters. As part of special lubricating compositions (alloys), rubidium is used as a highly effective lubricant in vacuum (rocket and space technology).

Rubidium hydroxide is used to prepare an electrolyte for low-temperature chemical current sources, and also as an additive to a solution of potassium hydroxide to improve its performance at low temperatures and increase the electrical conductivity of the electrolyte. Rubidium metal is used in hydride fuel cells.

Rubidium chloride alloyed with copper chloride is used for measuring high temperatures (up to 400 °C).

Rubidium vapor is used as a working fluid in lasers, in particular, in rubidium atomic clocks.

Rubidium chloride is used in fuel cells as an electrolyte, and the same can be said for rubidium hydroxide, which is very effective as an electrolyte in fuel cells using direct oxidation of coal.

Rubidium is used in solar cells (it has a very low electron work function). Rb 2 CO 3 is used as a catalyst.

RUBIDIUM, Rb (a. rubidium; n. Rubidium; f. rubidium; i. rubidio), is a chemical element of group I of the periodic system of Mendeleev, atomic number 37, atomic mass 85.4678; refers to alkali metals. It occurs in nature as a mixture of two stable isotopes: 85 Rb (72.15%) and 87 Rb (27.85%), the latter is radioactive and, emitting a b-particle, turns into the stable isotope 87 Sr. There are also 19 artificial isotopes of rubidium known.

Discovered by German scientists R. Bunsen and G. Kirchhoff in 1861 during a spectral study of sediment evaporated from the mineral waters of the Black Forest. Scientists gave the name to the element based on the color of the most characteristic red lines of its spectrum (from the Latin rubidus - red). Metallic rubidium was first obtained by R. Bunsen in 1863.

Properties of rubidium

Rubidium is a soft, silvery-white metal; crystal lattice is cubic, body-centered: a = 0.57 nm. Density 1525 kg/m3; melting point 39.47°C; boiling point 685°C; thermal conductivity l 22.2 W/(m.K); heat capacity Ср0 31.09 J/(mol.K). Specific electrical resistance 11.6.10 -6 Ohm.cm, temperature coefficient of linear expansion 90.10 -6 K -1.

Oxidation state +1. Instantly ignites in air, rubidium combines violently with oxygen, giving rubidium peroxide (Rb 2 O 2) and rubidium superoxide (RbO 2). Rubidium reacts explosively with water, releasing hydrogen and forming a solution of rubidium hydroxide (RbOH), which is similar in properties to alkali metal hydroxides. Rubidium reacts with all inorganic acids. Almost all rubidium compounds are highly soluble in water.

Rubidium in nature

Rubidium in a dispersed state is quite widespread in nature, however, despite the relatively high content in the earth's crust (1.5-10 -2%, i.e. more than copper, zinc and other elements), rubidium does not form its own minerals . As an isomorphic impurity, rubidium is included in minerals of other alkali metals and, above all, potassium. Compared to potassium, rubidium is concentrated in minerals at later stages of differentiation. Rubidium-rich minerals include concentrator minerals: pollucite, lepidolite, zinnwaldite, amazonite, biotite. The average content of rubidium in rocks increases in the series from basic to acidic from 0.1.10 -4 to 1.7.10 -4 g/t. A relatively high concentration of rubidium is observed in minerals of low-temperature pegmatite veins (up to 1-3% rubidium). The main industrial reserves of rubidium are concentrated in

Rubidium element is a white alkali metal with a metallic luster (see photo). It is easy to melt; this process occurs at a temperature of only 39°C. In all its characteristics, the element is similar to potassium and sodium. The name Rubidium is lat. dark red was not assigned to him for his natural coloring. German scientists Bunsen and Kirchhoff examined the new substance in a spectrograph and noticed red lines.

Rubidium is a very active element, but its characteristic feature is that most reactions occur explosively, and combustion is accompanied by a bright violet flame. In a similar way, interaction occurs with all known elements, regardless of their nature (metal-non-metal). Store it in vessels with dry kerosene or in a vacuum. In addition to being active, rubidium is also a radioactive element that gradually turns into strontium.

This substance is, by its nature, very unique. When exposed to light, it becomes a source of electric current. This phenomenon is called the photoelectric effect, and allows the element to be used for the manufacture of photocells used in cinema, television, and remote control of automation. Rubidium is valued very highly, and therefore consumption is quite small (several tens of kilograms per year).

It is also used in the manufacture of measuring instruments, as components of lubricants for rocket and space technology operating in vacuum conditions, and in X-ray equipment. It is thanks to the content of rubidium and strontium in rocks that geologists are able to determine their age.

In nature, rubidium is quite common, but only in the form of impurities. Its salts are often found in mineral springs and volcanic rocks.

Effect of rubidium and its biological role

The effect of a macroelement on a biological organism is associated with its concentration in certain organs: bone tissue, lungs, brain, ovaries. Its absorption from food occurs in the gastrointestinal tract, and it is excreted through natural secretions.

Scientists have not yet sufficiently studied the effect of the element on humans, but without a doubt, it plays a significant role in the body and has the following effect:

can to some extent replace potassium and play its role in enzyme activation;
has an antihistamine effect (fights the effects of allergens);
weakens inflammatory processes in cells and the body as a whole;
restores the balance of the central nervous system and has a calming effect.

Today, scientists are studying the effect of the element on stimulating blood circulation and using these properties to treat hypotension. Another famous doctor S. Botkin noticed in 1898 that rubidium chloride can increase pressure in the arteries and associated this with the process of vasoconstriction and activation of the cardiovascular system.

It has also been noted that microdoses of the element can cause red blood cells to resist harmful effects and increase the mass of hemoglobin in them. This in turn leads to increased immunity.

Most often, rubidium is studied in combination with cesium. The salts of these elements help to endure hypoxia - lack of oxygen.

We hope that this element will reveal many more of its unique abilities to the medical and scientific world.

Daily norm

The daily macronutrient requirement for an adult is approximately 1-2 mg. It is absorbed by the body quite quickly - after 1-1.5 hours you can find its content in the blood. In total, human tissues and organs contain about 1 gram of rubidium.

Deficiency of a chemical element in the body

Macronutrient deficiency and its effects on the human body have been practically unexplored. The experiments were carried out only on animals and their reaction was as follows:

loss of appetite, and even complete refusal to eat;
growth retardation, slow development, shortened life expectancy;
premature birth, miscarriages;
abnormalities in fetal development and decreased fertility.

Excess rubidium

An excess of a macroelement can cause dangerous complications due to the fact that rubidium belongs to the same category of poisonous and toxic elements as arsenic and sulfuric acid. Overdoses can cause great harm to health and even death.

The reason for such large doses may be work in enterprises where substance compounds are used that penetrate the body with vapors and dust. Theoretically, one of the reasons could be excessive intake of the element from food and water.

A slight increase in the level of a macronutrient can lead to migraines, insomnia, diseases and inflammation of the lungs and respiratory organs, rapid heartbeat (arrhythmias), skin allergies and increased levels of proteins in the urine. If poisoning is caused by the accumulation of critical masses of an element, then the consequences are similar to those caused by a deficiency of the element: slower growth and development, shortened life span.

Uniqueness again? The upside is that you need to be taking more than 1000 mg daily for these symptoms to occur, which is already very difficult.

Treatment of poisoning is carried out with substances that, when reacting with toxins, form compounds that easily dissolve in water and are excreted by the kidneys. Basically it is a complexing agent based on potassium or sodium. Drugs are also used to relieve characteristic symptoms.

What are the sources of the element?

The list of foods containing rubidium mainly consists of plant foods. Here are the most basic of them: eggplants, ginger, potatoes, beets, tomatoes, garlic, onions, mushrooms (champignons and porcini mushrooms), many fruits and dried fruits, nuts (almonds, walnuts and pine, hazelnuts, pistachios), sunflower seeds, cereals , legumes. Our body receives the largest amount from tea and coffee (about 40% of the total amount) and mineral water, depending on the origin.

This element is capable of accumulating in living tissues, especially in marine organisms. Therefore, eating seafood will help you get the required amount of rubidium.

Indications for use

Indications for prescribing a macronutrient are based on the nature of the effect on the human body. Its main medicinal purpose is the treatment of nervous system disorders. Even 100 years ago, it was actively used to get rid of epilepsy. Today it is used as a neurotropic drug to strengthen the nervous system.

It may also be necessary in the treatment of allergic diseases, muscle weakness, and anemia.

The content of the article

RUBIDIUM(Rubidium) Rb, a chemical element of the 1st (Ia) group of the Periodic table. Alkaline element. Atomic number 37, relative atomic mass 85.4678. It occurs in nature as a mixture of the stable isotope 85 Rb (72.15%) and the radioactive isotope 87 Rb (27.86%) with a half-life of 4.8. 10 10 years. Another 26 radioactive isotopes of rubidium with mass numbers from 75 to 102 and half-lives from 37 ms (rubidium-102) to 86 days (rubidium-83) have been artificially obtained.

Oxidation state +1.

Rubidium was discovered in 1861 by German scientists Robert Bunsen and Gustav Kirchhoff and was one of the first elements discovered by spectroscopy, which was invented by Bunsen and Kirchhoff in 1859. The name of the element reflects the color of the brightest line in its spectrum (from the Latin rubidus deep red) .

While studying various minerals with a spectroscope, Bunsen and Kirchhoff noticed that one of the lepidolite samples sent from Rosen (Saxony) produced lines in the red region of the spectrum. (Lepidolite is a mineral of potassium and lithium, which has the approximate composition K 2 Li 3 Al 4 Si 7 O 21 (OH,F) 3.) These lines were not found in the spectra of any known substance. Soon, similar dark red lines were discovered in the spectrum of sediment obtained after the evaporation of water from samples taken from mineral springs in the Black Forest. However, the content of the new element in the tested samples was negligible, and in order to extract more or less noticeable quantities, Bunsen had to evaporate over 40 m 3 of mineral waters. From the evaporated solution he precipitated a mixture of potassium, rubidium and cesium chloroplatinates. To separate rubidium from its closest relatives (and especially from a large excess of potassium), Bunsen subjected the precipitate to repeated fractional crystallization and obtained rubidium and cesium chlorides from the least soluble fraction and then converted them into carbonates and tartrates (tartaric acid salts), which allowed for even better purification rubidium and free it from the bulk of cesium. Bunsen managed to obtain not only individual rubidium salts, but also the metal itself. Metallic rubidium was first obtained by reducing the acid salt of rubidium hydrogen tartrate with soot.

A quarter of a century later, Russian chemist Nikolai Nikolaevich Beketov proposed another method for obtaining metal rubidium - by reducing it from hydroxide with aluminum powder. He carried out this process in an iron cylinder with a gas outlet tube, which was connected to a glass refrigerator tank. The cylinder was heated on a gas burner, and a violent reaction began in it, accompanied by the release of hydrogen and the sublimation of rubidium in the refrigerator. As Beketov himself wrote, “rubidium is driven gradually, flowing down like mercury, and even retaining its metallic luster due to the fact that the projectile is filled with hydrogen during the operation.”

Distribution of rubidium in nature and its industrial extraction. The content of rubidium in the earth's crust is 7.8·10 3%. This is approximately the same as for nickel, copper and zinc. In terms of abundance in the earth's crust, rubidium is approximately in 20th place, but in nature it is in a dispersed state, rubidium is a typical trace element. The intrinsic minerals of rubidium are unknown. Rubidium is found together with other alkaline elements and always accompanies potassium. It is found in many rocks and minerals, particularly in North America, South Africa and Russia, but its concentration there is extremely low. Only lepidolites contain slightly more rubidium, sometimes 0.2%, and occasionally up to 13% (in terms of Rb 2 O).

Rubidium salts are dissolved in the water of seas, oceans and lakes. Their concentration here is very low, on average about 100 µg/l. In some cases, the content of rubidium in water is higher: in the Odessa estuaries it turned out to be 670 µg/l, and in the Caspian Sea 5700 µg/l. Increased rubidium content has also been found in some mineral springs in Brazil.

From seawater, rubidium passed into potassium salt deposits, mainly into carnallites. In the Strassfurt and Solikamsk carnallites, the rubidium content ranges from 0.037 to 0.15%. The mineral carnallite is a complex chemical compound formed by potassium and magnesium chlorides with water; its formula is KCl MgCl 2 6H 2 O. Rubidium gives a salt of similar composition RbCl MgCl 2 6H 2 O, and both salts potassium and rubidium have the same structure and form a continuous series of solid solutions, crystallizing together. Carnallite is highly soluble in water, so opening the mineral is not difficult. Rational and economical methods for extracting rubidium from carnallite, along with other elements, have now been developed and described in the literature.

However, most mined rubidium is obtained as a by-product in the production of lithium from lepidolite. After lithium is isolated in the form of carbonate or hydroxide, rubidium is precipitated from mother liquors in the form of a mixture of aluminum rubidium, aluminum potassium and aluminum cesium alum MAl(SO 4) 2 12H 2 O (M = Rb, K, Cs). The mixture is separated by repeated recrystallization. Rubidium is also isolated from the waste electrolyte obtained when producing magnesium from carnallite. Rubidium is isolated from it by sorption on precipitates of iron or nickel ferrocyanides. Then the ferrocyanides are calcined and rubidium carbonate with impurities of potassium and cesium is obtained. When obtaining cesium from pollucite, rubidium is extracted from the mother liquors after the precipitation of Cs 3 . Rubidium can also be extracted from technological solutions formed during the production of alumina from nepheline.

To extract rubidium, extraction and ion exchange chromatography methods are used. High purity rubidium compounds are prepared using polyhalides.

Much of the rubidium produced is recovered during the production of lithium, so the emergence of great interest in lithium for use in fusion processes in the 1950s led to an increase in the production of lithium, and therefore rubidium, and therefore rubidium compounds became more accessible.

Rubidium is one of the few chemical elements whose resources and production capabilities are greater than the current needs for it. There are no official statistics on the production and use of rubidium and its compounds. It is believed that the annual production of rubidium is about 5 tons.

The market for rubidium is very small. There is no active trade in the metal, and there is no market price for it. Prices set by companies selling rubidium and its compounds vary tenfold.

Characteristics of a simple substance, industrial production and use of metallic rubidium. Rubidium is a soft, silvery-white metal. At normal temperatures it has an almost paste-like consistency. Rubidium melts at 39.32° C, boils at 687.2° C. Rubidium vapor is colored greenish-blue.

Rubidium is highly reactive. In air, it instantly oxidizes and ignites, forming superoxide RbO 2 (with an admixture of peroxide Rb 2 O 2):

Rb + O 2 = RbO 2, 2Rb + O 2 = Rb 2 O 2

Rubidium reacts explosively with water to form hydroxide RbOH and release hydrogen: 2Rb + 2H 2 O = 2RbOH + H 2.

Rubidium combines directly with most nonmetals. However, it does not interact with nitrogen under normal conditions. Rubidium nitride Rb 3 N is formed by passing an electric discharge in liquid nitrogen between electrodes made of rubidium.

Rubidium reduces oxides to simple substances. It reacts with all acids to form the corresponding salts, and with alcohols it gives alcoholates:

2Rb + 2C 2 H 5 OH = 2C 2 H 5 ORb + H 2

Rubidium dissolves in liquid ammonia, producing blue solutions containing solvated electrons and exhibiting electronic conductivity.

Rubidium forms alloys and intermetallic compounds with many metals. The RbAu compound, in which the bond between metals is partially ionic in nature, is a semiconductor.

Metallic rubidium is obtained mainly by the reduction of rubidium compounds (usually halides) with calcium or magnesium:

2RbCl + 2Ca = 2Rb + CaCl 2

Rb 2 CO 3 + 3Mg = 2Rb + 3MgO + C

The reaction of rubidium halide with magnesium or calcium is carried out at 600-800 ° C and 0.1 Pa. The product is purified from impurities by rectification and vacuum distillation.

Rubidium can be obtained electrochemically from a melt of rubidium halide on a liquid lead cathode. From the resulting lead-rubidium alloy, rubidium is isolated by distillation in a vacuum.

In small quantities, rubidium is obtained by reducing rubidium chromate Rb 2 CrO 4 with zirconium or silicon powder, and high-purity rubidium is obtained by slow thermal decomposition of rubidium azide RbN 3 in a vacuum at 390-395 ° C.

Metallic rubidium is a component of the cathode material for photocells and photoelectric multipliers, although rubidium photocathodes are inferior to some others, in particular cesium, in sensitivity and range of action. It is part of lubricant compositions used in jet and space technology. Rubidium vapor is used in electric discharge tubes.

Metallic rubidium is a component of catalysts (it is applied to active aluminum oxide, silica gel, metallurgical slag) for the oxidation of organic impurities during the production of phthalic anhydride, as well as the process of producing cyclohexane from benzene. In its presence, the reaction occurs at lower temperatures and pressures than when catalysts are activated by sodium or potassium, and it is almost uninterrupted by poisons that are “deadly” for conventional catalysts—substances containing sulfur.

Rubidium is dangerous to handle. It is stored in special glass ampoules in an argon atmosphere or in sealed steel vessels under a layer of dehydrated mineral oil.

Rubidium compounds. Rubidium forms compounds with all common anions. Almost all rubidium salts are highly soluble in water. Like potassium, the salts Rb 2 SiF 6 and Rb 2 PtCl 6 are slightly soluble.

Compounds of rubidium with oxygen.

Rubidium forms numerous oxygen compounds, including Rb 2 O oxide, Rb 2 O 2 peroxide, RbO 2 superoxide, and RbO 3 ozonide. All of them are colored, for example, Rb 2 O is bright yellow, and RbO 2 is dark brown. Rubidium superoxide is formed when rubidium is burned in air. Rubidium peroxide is obtained by oxidizing rubidium dissolved in anhydrous ammonia with anhydrous hydrogen peroxide, and rubidium oxide by heating a mixture of rubidium metal and its peroxide. Oxide, peroxide and superoxide are thermally stable, they melt at a temperature of about 500 ° C.

Using X-ray diffraction analysis, it was shown that the compound of composition Rb 4 O 6, obtained in the solid state by the reaction of Rb 2 O 2 with RbO 2 in a ratio of 1:2, has the composition. At the same time, diatomic oxygen anions of different types (peroxide and superoxide) in a cubic unit cell are indistinguishable even at 60° C. This compound melts at 461° C.

Rubidium ozonide RbO 3 is formed by the action of ozone on anhydrous RbOH powder at low temperature:

4RbOH + 4O 3 = 4RbO 3 + 2H 2 O + O 2

Partial oxidation of rubidium at low temperatures produces a compound with the composition Rb 6 O, which decomposes above 7.3 ° C to form shiny copper-colored crystals with the composition Rb 9 O 2. When exposed to water, the Rb 9 O 2 compound ignites. At 40.2°C it melts with decomposition and the formation of Rb 2 O and Rb in a ratio of 2:5.

Rubidium carbonate Rb 2 CO 3 melts at 873° C, is highly soluble in water: at 20° C, 450 g of rubidium carbonate dissolves in 100 g of water.

In 1921, German chemists Fischer Franz (1877–1947) and Hans Tropsch (1889–1935) found that rubidium carbonate was an excellent catalyst component for the production of synthetic petroleum synthol (a mixture of alcohols, aldehydes and ketones, formed from water gas at 410° C and a pressure of 140150 atm in the presence of a special catalyst).

Rubidium carbonate has a positive effect on the polymerization of amino acids; with its help, synthetic polypeptides with a molecular weight of up to 40,000 are obtained, and the reaction proceeds very quickly.

Rubidium hydride RbH is obtained by the interaction of simple substances when heated under a pressure of 510 MPa in the presence of a catalyst:

2Rb + H 2 = 2RbH

This compound melts at 585° C; decomposes when exposed to water.

Rubidium halides RbF, RbCl, RbBr, RbI are prepared by reacting rubidium hydroxide or carbonate with the corresponding hydrohalic acids, by reacting rubidium sulfate with soluble barium halides, and by passing rubidium sulfate or nitrate through an ion exchange resin.

Rubidium halides are highly soluble in water, but less soluble in organic solvents. They dissolve in aqueous solutions of hydrohalic acids, forming hydrohalides in solution, the stability of which decreases from RbHF 2 hydrodifluoride to RbHI 2 hydrodiiodide.

Rubidium fluoride is included in special glasses and compositions for heat accumulation. It is an optical material, transparent in the range of 916 microns. Rubidium chloride serves as an electrolyte in fuel cells. It is added to special iron castings to improve their mechanical properties, and is a component of the cathode material of cathode ray tubes.

For mixtures of rubidium chlorides with copper, silver or lithium chlorides, the electrical resistance drops so sharply with increasing temperature that they can become very convenient thermistors in various electrical installations operating at temperatures of 150-290 ° C.

Rubidium iodide is used as a component of luminescent materials for fluorescent screens, solid electrolytes in chemical current sources. The compound RbAg 4 I 5 has the highest electrical conductivity of all known ionic crystals. It can be used in thin film batteries.

Complex connections. Rubidium is not characterized by the formation of covalent bonds. Its most stable complexes are with polydentate ligands, such as crown ethers, where it usually exhibits a coordination number of 6.

Another group of very effective ligands that have recently been used to coordinate alkali element cations are macrocyclic polydentate ligands, which the French organic chemist Jean Marie Lehn called cryptands (Fig. 1).

Rubidium forms the CNS complex. H 2 O, in which the cryptand N((CH 2 CH 2 O) 2 CH 2 CH 2 ) 3 N (crypt) encloses the cation in a coordination polyhedron shaped like a double-capped trigonal prism (Fig. 2).

Rubidium ozonide forms stable solutions in organic solvents (such as CH 2 Cl 2, tetrahydrofuran or CH 3 CN) if the cation is coordinated by crown ethers or cryptands. Slow evaporation of ammonia solutions of such complexes leads to the formation of red crystals. X-ray diffraction analysis of the compound showed that the coordination number of the rubidium atom is 9. It forms six bonds with the crown ether, two with the O 3 ion and one with the ammonia molecule.

Application of rubidium isotopes.

Rubidium-87 spontaneously emits electrons (b-radiation) and turns into an isotope of strontium. About 1% of strontium was formed on Earth in this very way, and if you determine the ratio of strontium and rubidium isotopes with a mass number of 87 in any rock, you can calculate its age with great accuracy. This method is suitable for the most ancient rocks and minerals. With its help, it was established, for example, that the oldest rocks of the American continent arose 2100 million years ago.

The radionuclide rubidium-82, with a half-life of 76 s, is used in diagnostics. With its help, in particular, the condition of the myocardium is assessed. The isotope is injected into the patient's bloodstream and the blood flow is analyzed using positron emission tomography (PET).

Elena Savinkina

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