Atomic structure of strontium. Strontium metal

Strontium- element of the main subgroup of the second group, fifth period periodic table chemical elements of D.I. Mendeleev, with atomic number 38. Denoted by the symbol Sr (lat. Strontium). The simple substance strontium (CAS number: 7440-24-6) is a soft, malleable and ductile alkaline earth metal of a silvery-white color. It has high chemical activity; in air it quickly reacts with moisture and oxygen, becoming covered with a yellow oxide film.

History and origin of the name

The new element was discovered in the mineral strontianite, found in 1764 in a lead mine near the Scottish village of Stronshian, which later gave its name to the new element. The presence of a new metal oxide in this mineral was discovered almost 30 years later by William Cruickshank and Ader Crawford. Isolated in its pure form by Sir Humphry Davy in 1808.

Presence in nature

Strontium is found in sea ​​water(0.1 mg/l), in soils (0.035 wt%).

In nature, strontium occurs as a mixture of 4 stable isotopes 84 Sr (0.56%), 86 Sr (9.86%), 87 Sr (7.02%), 88 Sr (82.56%).

Obtaining Strontium

Three ways to obtain strontium metal:

— thermal decomposition of some compounds
— electrolysis
- reduction of oxide or chloride

The main industrial method for producing strontium metal is the thermal reduction of its oxide with aluminum. Next, the resulting strontium is purified by sublimation.

The electrolytic production of strontium by electrolysis of a melted mixture of SrCl 2 and NaCl is not widespread due to the low current efficiency and contamination of strontium with impurities.

The thermal decomposition of strontium hydride or nitride produces finely dispersed strontium, which is prone to easy ignition.

Physical properties

Strontium is a soft, silvery-white metal that is malleable and ductile and can be easily cut with a knife.

Polymorphic - three of its modifications are known. Up to 215 o C, the cubic face-centered modification (α-Sr) is stable, between 215 and 605 o C - hexagonal (β-Sr), above 605 o C - cubic body-centered modification (γ-Sr).

Melting point - 768 o C, Boiling point - 1390 o C.

Chemical properties

Strontium in its compounds always exhibits a valence of +2. The properties of strontium are close to calcium and barium, occupying an intermediate position between them.

In the electrochemical voltage series, strontium is among the most active metals (its normal electrode potential is −2.89 V. It reacts vigorously with water, forming hydroxide:

Sr + 2H 2 O = Sr(OH) 2 + H 2

Interacts with acids, displaces heavy metals from their salts. It reacts weakly with concentrated acids (H 2 SO 4, HNO 3).

Strontium metal quickly oxidizes in air, forming a yellowish film, in which, in addition to SrO oxide, SrO 2 peroxide and Sr 3 N 2 nitride are always present. When heated in air, it ignites; powdered strontium in air is prone to self-ignition.

Reacts vigorously with non-metals - sulfur, phosphorus, halogens. Interacts with hydrogen (above 200 o C), nitrogen (above 400 o C). Practically does not react with alkalis.

At high temperatures reacts with CO 2 to form carbide:

5Sr + 2CO 2 = SrC 2 + 4SrO

Easily soluble strontium salts with the anions Cl - , I - , NO 3 - . Salts with anions F -, SO 4 2-, CO 3 2-, PO 4 3- are slightly soluble.

Application

The main areas of application of strontium and its chemical compounds are the radio-electronic industry, pyrotechnics, metallurgy, food industry.

Metallurgy

Strontium is used for alloying copper and some of its alloys, for introduction into battery lead alloys, for desulfurization of cast iron, copper and steels.

Metallothermy

Strontium with a purity of 99.99–99.999% is used for the reduction of uranium.

Magnetic materials

Magnetically hard strontium ferrites are widely used materials for the production of permanent magnets.

Pyrotechnics

In pyrotechnics, strontium carbonate, nitrate, and perchlorate are used to color the flame brick-red. The magnesium-strontium alloy has strong pyrophoric properties and is used in pyrotechnics for incendiary and signal compositions.

Isotopes

Radioactive 90 Sr (half-life 28.9 years) is used in the production of radioisotope current sources in the form of strontium titanate (density 4.8 g/cm³, and energy release about 0.54 W/cm³).

Nuclear energy

Strontium uranate plays important role when producing hydrogen (strontium-uranate cycle, Los Alamos, USA) by thermochemical method (atomic-hydrogen energy), and in particular, methods are being developed for the direct fission of uranium nuclei in the composition of strontium uranate to produce heat from the decomposition of water into hydrogen and oxygen.

High temperature superconductivity

Strontium oxide is used as a component of superconducting ceramics.

Chemical current sources

Strontium fluoride is used as a component of solid-state fluorine batteries with enormous energy capacity and energy density.

Strontium alloys with tin and lead are used for casting battery current leads. Strontium-cadmium alloys for galvanic cell anodes.

Biological role

Effect on the human body

The effect on the human body of natural (non-radioactive, low-toxic and, moreover, widely used for the treatment of osteoporosis) and radioactive isotopes of strontium should not be confused. The strontium isotope 90 Sr is radioactive with a half-life of 28.9 years. 90 Sr undergoes β-decay, transforming into radioactive 90 Y (half-life 64 hours). Complete decay of strontium-90 trapped in environment, will happen only in a few hundred years. 90 Sr is formed when nuclear explosions and emissions from nuclear power plants. By chemical reactions Radioactive and non-radioactive isotopes of strontium are practically the same. Natural strontium - component microorganisms, plants and animals. Regardless of the route and rhythm of entry into the body, soluble strontium compounds accumulate in the skeleton. IN soft tissues less than 1% is retained. The route of entry influences the amount of strontium deposits in the skeleton. The behavior of strontium in the body is influenced by species, gender, age, as well as pregnancy and other factors. For example, males have higher levels of deposits in their skeletons than females. Strontium is an analogue of calcium. Strontium accumulates at a high rate in the body of children up to the age of four, when bone tissue is actively being formed. Strontium metabolism changes in certain diseases of the digestive system and of cardio-vascular system. Routes of entry:

1. water (the maximum permissible concentration of strontium in water in the Russian Federation is 8 mg/l, and in the USA - 4 mg/l)
2. food (tomatoes, beets, dill, parsley, radishes, radishes, onions, cabbage, barley, rye, wheat)
3. intratracheal delivery
4. through the skin (cutaneous)
5. inhalation (through air)
6. From plants or through animals, strontium-90 can directly pass into the human body.
7. people whose work involves strontium (in medicine, radioactive strontium is used as applicators in the treatment of skin and eye diseases. The main areas of application of natural strontium are the radio-electronic industry, pyrotechnics, metallurgy, metallothermy, food industry, production of magnetic materials, radioactive - etc. -in nuclear electric batteries. nuclear-hydrogen energy, radioisotope thermoelectric generators, etc.)

The influence of non-radioactive strontium is extremely rare and only when exposed to other factors (calcium and vitamin D deficiency, malnutrition, imbalances in the ratio of microelements such as barium, molybdenum, selenium, etc.). Then it can cause “strontium rickets” and “strontium disease” in children - damage and deformation of joints, growth retardation and other disorders. On the contrary, radioactive strontium almost always has a negative effect on the human body:

1. deposited in the skeleton (bones), affects bone tissue and bone marrow, which leads to the development of radiation sickness, tumors of hematopoietic tissue and bones.
2. causes leukemia and malignant tumors(cancer) of bones, as well as liver and brain damage

Isotopes

Strontium-90

The strontium isotope 90 Sr is radioactive with a half-life of 28.79 years. 90 Sr undergoes β-decay, turning into radioactive yttrium 90 Y (half-life 64 hours). 90 Sr is formed during nuclear explosions and emissions from nuclear power plants.

Strontium is an analogue of calcium and is able to be firmly deposited in bones. Long-term radiation exposure to 90 Sr and 90 Y affects bone tissue and bone marrow, which leads to the development of radiation sickness, tumors of hematopoietic tissue and bones.

Strontium metal is now produced by the aluminothermic method. SrO oxide is mixed with aluminum powder or shavings and at a temperature of 1100...1150°C in an electric vacuum oven (pressure 0.01 mm Hg) the reaction begins:

4SrO + 2Al → 3Sr + Al 2 O 3 SrO.

Electrolysis of strontium compounds (a method used by Davy) is less effective.

Applications of metal strontium

Strontium is an active metal. This prevents its widespread use in technology. But, on the other hand, the high chemical activity of strontium makes it possible to use it in certain areas of the national economy. In particular, it is used in the smelting of copper and bronze - strontium binds sulfur, phosphorus, carbon and increases the fluidity of slag. Thus, strontium helps purify the metal from numerous impurities. In addition, the addition of strontium increases the hardness of copper without almost reducing its electrical conductivity. Strontium is introduced into electric vacuum tubes to absorb remaining oxygen and nitrogen and make the vacuum deeper. Repeatedly purified strontium is used as a reducing agent in the production of uranium.

Additionally:

Strontium-90 (English strontium-90) - radioactive nuclide chemical element strontium With atomic number 38 andmass number 90. Formed mainly when nuclear fission V nuclear reactors And nuclear weapons.

To the environment 90 Sr enters mainly during nuclear explosions and emissions from NPP.

Strontium is an analogue calcium and is able to be firmly deposited in the bones. Long-term radiation exposure 90 Sr and its breakdown products affect bone tissue and bone marrow, which leads to the development radiation sickness, tumors of hematopoietic tissue and bones.

Application:

90 Sr is used in production radioisotope energy sources in the form of strontium titanate (density 4.8 g/cm³, energy release about 0.54 W/cm³).

One of the wide applications 90 Sr - control sources of dosimetric instruments, including military ones and Civil Defense. The most common - type “B-8” is made as a metal substrate containing in a recess a drop of epoxy resin containing a compound 90 Sr. To provide protection against the formation of radioactive dust through erosion, the preparation is covered with a thin layer of foil. In fact, such sources of ionizing radiation are a complex 90 Sr- 90 Y, since yttrium is continuously formed during the decay of strontium. 90 Sr- 90 Y is an almost pure beta source. Unlike gamma radioactive drugs, beta drugs can be easily shielded with a relatively thin (about 1 mm) layer of steel, which led to the choice of beta drug for testing purposes, starting with the second generation of military dosimetric equipment (DP-2, DP-12, DP- 63).

Strontium is a silvery-white, soft, ductile metal. Chemically it is very active, like all alkaline earth metals. Oxidation state + 2. Strontium directly combines when heated with halogens, phosphorus, sulfur, carbon, hydrogen and even nitrogen (at temperatures above 400°C).

Conclusion

So, strontium is often used in chemistry, metallurgy, feather technology, nuclear power engineering, etc. And therefore, this chemical element is making its way into industry more and more confidently, and the demand for it is constantly growing.

Strontium is also useful in medicine. The effect of natural strontium on the human body (low toxic, widely used for the treatment of osteoporosis). Radioactive strontium almost always has a negative effect on the human body.

Will nature be able to satisfy humanity’s needs for this metal?

In nature there are quite large so-called volcanogenic-sedimentary deposits of strontium, for example in the deserts of California and Arizona in the USA (By the way, it has been noted that strontium “loves” hot climates, so it is much less common in northern countries.). During the Tertiary era, this area was the scene of violent volcanic activity.

The thermal waters that rose along with lava from the bowels of the earth were rich in strontium. Lakes located among volcanoes accumulated this element, forming very substantial reserves over thousands of years.

Several years ago, geologists discovered a significant deposit of celestine in the mountains of Turkmenistan. Blue layers of this valuable mineral lie on the slopes of gorges and deep canyons of Kushtangtau, a mountain range in the southwestern part of the Pamir-Alai. There is no doubt that the Turkmen “heavenly” stone will successfully serve our national economy.

Nature is not characterized by haste: now man is using strontium reserves, which she began to create millions of years ago. But even today, in the depths of the earth, in the thickness of the seas and oceans, complex chemical processes occur, accumulations of valuable elements arise, new treasures are born, but they will no longer go to us, but to our distant, distant descendants.

Bibliography

Encyclopedia Around the World

http://www.krugosvet.ru/enc/nauka_i_tehnika/himiya/STRONTSI.html?page=0.3

Wikipedia "Strontium"

http://ru.wikipedia.org/wiki/%D0%A1%D1%82%D1%80%D0%BE%D0%BD%D1%86%D0%B8%D0%B9

3. Popular library of chemical elements

Strontium is an element of the main subgroup of the second group, the fifth period of the periodic system of chemical elements of D.I. Mendeleev, with atomic number 38. It is designated by the symbol Sr (lat. Strontium). The simple substance strontium (CAS number: 7440-24-6) is a soft, malleable and ductile alkaline earth metal of silver-white color. It has high chemical activity; in air it quickly reacts with moisture and oxygen, becoming covered with a yellow oxide film.

History and origin of the name

The new element was discovered in the mineral strontianite, found in 1764 in a lead mine near the Scottish village of Stronshian, which later gave its name to the new element. The presence of a new metal oxide in this mineral was established in 1787 by William Cruickshank and Adair Crawford. Isolated in its pure form by Sir Humphry Davy in 1808.

Receipt

There are 3 ways to obtain strontium metal:
1. thermal decomposition of some compounds
2. electrolysis
3. reduction of oxide or chloride
The main industrial method for producing strontium metal is the thermal reduction of its oxide with aluminum. Next, the resulting strontium is purified by sublimation.
The electrolytic production of strontium by electrolysis of a melted mixture of SrCl 2 and NaCl is not widespread due to the low current efficiency and contamination of strontium with impurities.
The thermal decomposition of strontium hydride or nitride produces finely dispersed strontium, which is prone to easy ignition.

Chemical properties

Strontium in its compounds always exhibits a valence of +2. The properties of strontium are close to calcium and barium, occupying an intermediate position between them.
In the electrochemical voltage series, strontium is among the most active metals (its normal electrode potential is −2.89 V). Reacts vigorously with water to form hydroxide:
Sr + 2H 2 O = Sr(OH) 2 + H 2

Interacts with acids, displaces heavy metals from their salts. It reacts weakly with concentrated acids (H 2 SO 4, HNO 3).
Strontium metal quickly oxidizes in air, forming a yellowish film, in which, in addition to SrO oxide, SrO 2 peroxide and Sr 3 N 2 nitride are always present. When heated in air, it ignites; powdered strontium in air is prone to self-ignition.
Reacts vigorously with non-metals - sulfur, phosphorus, halogens. Interacts with hydrogen (above 200°C), nitrogen (above 400°C). Practically does not react with alkalis.
At high temperatures it reacts with CO 2, forming carbide:
5Sr + 2CO 2 = SrC 2 + 4SrO

Easily soluble strontium salts with the anions Cl - , I - , NO 3 - . Salts with anions F -, SO 4 2-, CO 3 2-, PO 4 3- are slightly soluble.

STRONTIUM (Strontium, Sr) - a chemical element of D.I. Mendeleev’s periodic table, a subgroup of alkaline earth metals. In the human body, S. competes with calcium (see) for inclusion in the crystal lattice of bone oxyapatite (see). 90 Sr, one of the longest-lived radioactive fission products of uranium (see), accumulating in the atmosphere and biosphere during testing nuclear weapons(see), poses a huge danger to humanity. Radioactive isotopes of S. are used in medicine for radiation therapy (see), as a radioactive label in diagnostic radiopharmaceuticals (see) in medical biol. research, as well as in nuclear electric batteries. S. compounds are used in flaw detectors, in sensitive instruments, in devices for combating static electricity; in addition, S. is used in radio electronics, pyrotechnics, metallurgy, chemical industry and during production ceramic products. S. compounds are non-toxic. When working with metal S., you should be guided by the rules for handling alkali metals (see) and alkaline earth metals (see).

S. was discovered as part of the mineral, later called strontianite SrC03, in 1787 near the Scottish city of Strontian.

The serial number of strontium is 38, atomic weight(mass) 87.62. Contents of S. in earth's crust averages 4-10 2 wt. %, in sea water - 0.013% (13 mg/l). The minerals strontianite and celestine SrSO 4 are of industrial importance.

The human body contains approx. 0.32 g of strontium, mainly in bone tissue, in the blood the concentration of S. is normally 0.035 mg/l, in urine - 0.039 mg/l.

S. is a soft silvery-white metal, melting point 770°, boiling point 1383°.

According to chemistry properties of S. are similar to calcium and barium (see), in compounds the valency of strontium is 4-2, chemically active, oxidizes when normal conditions water with the formation of Sr(OH) 2, as well as oxygen and other oxidizing agents.

S. enters the human body. arr. with plant foods, as well as with milk. It is absorbed in the small intestine and quickly exchanges with S. contained in the bones. The removal of S. from the body is enhanced by complexons, amino acids, and polyphosphates. The increased content of calcium and fluorine (see) in water prevents C.'s accumulation in the bones. When the concentration of calcium in the diet increases by 5 times, the accumulation of calcium in the body is reduced by half. Excessive intake of S. from food and water due to its increased content in the soil of certain geochemicals. provinces (for example, in certain districts Eastern Siberia) causes an endemic disease - Urov disease (see Kashin-Beck disease).

In bones, blood and other biol. S. substrates are determined by Ch. arr. spectral methods (see Spectroscopy).

Radioactive strontium

Natural S. consists of four stable isotopes with mass numbers 84, 86, 87 and 88, of which the last is the most common (82.56%). There are 18 known radioactive isotopes of S. (with mass numbers 78-83, 85, 89-99) and 4 isomers of isotopes with mass numbers 79, 83, 85 and 87 (see Isomerism).

In medicine, 90Sr is used for radiation therapy in ophthalmology and dermatology, as well as in radiobiological experiments as a source of beta radiation. 85Sr is produced either by irradiating a strontium target enriched in the 84Sr isotope with neutrons in a nuclear reactor, according to the reaction 84Sr (11.7) 85Sr, or is produced in a cyclotron, irradiating targets made of natural rubidium with protons or deuterons, for example, according to the reaction 85Rb (p, n) 85Sr. The radionuclide 85Sr decays with electron capture, emitting gamma radiation with an energy E gamma equal to 0.513 MeV (99.28%) and 0.868 MeV (< 0,1%).

87m Sr can also be obtained by irradiating a strontium target in a reactor according to the reaction 86Sr (n, gamma) 87mSr, but the yield of the desired isotope is small, in addition, the isotopes 85Sr and 89Sr are formed simultaneously with 87mSr. Therefore, 87niSr is usually obtained using an isotope generator (see Generators of radioactive isotopes) based on the parent isotope yttrium-87 - 87Y (T1/2 = 3.3 days). 87mSr decays with an isomeric transition, emitting gamma radiation with an Egamma energy of 0.388 MeV and partially with electron capture (0.6%).

89Sr is contained in fission products together with 90Sr, so 89Sr is obtained by irradiating natural carbon dioxide in a reactor. In this case, an 85Sr impurity is inevitably formed. The 89Sr isotope decays by emitting P-radiation with an energy of 1.463 MeV (approx. 100%). The spectrum also contains a very weak gamma-ray line with an energy E gamma equal to 0.95 MeV (0.01%).

90Sr is obtained by isolating uranium fission products from a mixture (see). This isotope decays by emitting beta radiation with an E beta energy of 0.546 Meu (100%), without accompanying gamma radiation. The decay of 90Sr leads to the formation of a daughter radionuclide 90Y, which decays (T1/2 = 64 hours) with the emission of p-radiation, consisting of two components with Ep equal to 2.27 MeV (99%) and 0.513 MeV (0 .02%). The decay of 90Y also emits very weak gamma radiation with an energy of 1.75 MeV (0.02%).

Radioactive isotopes 89Sr and 90Sr, present in nuclear industry waste and generated during nuclear weapons testing, can enter the human body through food, water, and air when the environment is polluted. Quantitative assessment of calcium migration in the biosphere is usually carried out in comparison with calcium. In most cases, when 90Sr moves from the previous link in the chain to the next, the concentration of 90Sr decreases per 1 g of calcium (the so-called discrimination coefficient); in adults in the body-diet link, this coefficient is 0.25.

Like soluble compounds of other alkaline earth elements, soluble compounds of S. are well absorbed from the gland. tract (10-60%), absorption of poorly soluble S. compounds (eg, SrTiO3) is less than 1%. The degree of absorption of S. radionuclides in the intestine depends on age. With an increase in calcium content in the diet, calcium accumulation in the body decreases. Milk helps increase the absorption of S. and calcium in the intestines. This is believed to be due to the presence of lactose and lysine in milk.

When inhaled, soluble SrTi03 compounds are quickly eliminated from the lungs, while poorly soluble SrTiO3 is exchanged in the lungs extremely slowly. Penetration of S. radionuclide through intact skin is approx. 1%. Through damaged skin (cut wound, burns, etc.)? as well as from subcutaneous tissue and muscle tissue, S. is absorbed almost completely.

S. is an osteotropic element. Regardless of the route and rhythm of entry into the body, soluble 90Sr compounds selectively accumulate in the bones. Less than 1% 90Sr is retained in soft tissues.

When administered intravenously, S. is very quickly eliminated from the bloodstream. Soon after administration, the concentration of S. in the bones becomes 100 times or more higher than in soft tissues. Some differences were noted in the accumulation of 90Sr in individual organs and tissues. Relatively higher concentrations of 90Sr in experimental animals are found in the kidneys, salivary and thyroid glands, and the lowest in the skin, bone marrow and adrenal glands. The concentration of 90Sr in the renal cortex is always higher than in medulla. S. initially lingers on bone surfaces (periosteum, endosteum), and then is distributed relatively evenly throughout the entire volume of the bone. However, the distribution of 90Sr in different parts of the same bone and in different bones appears to be uneven. In the first time after administration, the concentration of 90Sr in the epiphysis and metaphysis of the bones of experimental animals is approximately 2 times higher than in the diaphysis. 90Sr is released from the epiphysis and metaphysis faster than from the diaphysis: within 2 months. the concentration of 90Sr in the epiphysis and metaphysis of the bone decreases by 4 times, and in the diaphysis remains almost unchanged. Initially, 90Sr is concentrated in those areas where active bone formation occurs. Abundant blood and lymph circulation in the epimetaphyseal areas of the bone contributes to a more intense deposition of 90Sr in them compared to the diaphysis of the tubular bone. The amount of 90Sr deposition in animal bones is variable. A sharp decrease in 90Sr fixation in bones with age was found in all animal species. The deposition of 90Sr in the skeleton significantly depends on gender, pregnancy, lactation, and the state of the neuroendocrine system. Higher 90Sr deposition in the skeleton was observed in male rats. In the skeleton of pregnant females, 90Sr accumulates less (up to 25%) than in control animals. Lactation has a significant influence on the accumulation of 90Sr in the skeleton of females. When 90Sr is administered 24 hours after birth, 90Sr is retained in the skeleton of rats 1.5-2 times less than in non-lactating females.

The penetration of 90Sr into the tissues of the embryo and fetus depends on the stage of their development, the state of the placenta and the duration of circulation of the isotope in the mother’s blood. The greater the gestational age at the time of radionuclide administration, the greater is the penetration of 90Sr into the fetus.

To reduce the damaging effects of strontium radionuclides, it is necessary to limit their accumulation in the body. For this purpose, when the skin is contaminated, it is necessary to quickly decontaminate its exposed areas (with the “Zashchita-7” preparation, “Era” or “Astra” washing powders, NEDE paste). When strontium radionuclides are ingested orally, antidotes should be used to bind or absorb the radionuclide. Such antidotes include activated barium sulfate (adso-bar), polysurmin, alginic acid preparations, etc. For example, the drug adsobar, when taken immediately after radionuclides enter the stomach, reduces their absorption by 10-30 times. Adsorbents and antidotes should be prescribed immediately after detection of damage from strontium radionuclides, since delay in this case leads to sharp decline their positive action. At the same time, it is recommended to prescribe emetics (apomorphine) or perform copious gastric lavage, use saline laxatives, and cleansing enemas. If affected by dusty drugs, it is necessary to rinse the nose and mouth abundantly, expectorants (thermopsis with soda), ammonium chloride, calcium injections, and diuretics. In more late dates after a lesion, to reduce the deposition of S. radionuclides in the bones, it is recommended to use the so-called. stable strontium (S. lactate or S. gluconate). Large doses of calcium orally or intravenously MofyT replace stable strontium preparations if these are not available. Due to the good reabsorption of strontium radionuclides in the renal tubules, the use of diuretics is also indicated.

A certain reduction in the accumulation of S. radionuclides in the body can be achieved by creating a competitive relationship between them and a stable isotope of S. or calcium, as well as by creating a deficiency of these elements in cases where the S. radionuclide is already fixed in the skeleton. However effective means The decorporation of radioactive strontium from the body has not yet been found.

The minimum significant activity that does not require registration or permission from the State Sanitary Supervision authorities for 85mSr, 85Sr, 89Sr and 90Sr is 3.5*10 -8, 10 -10, 2.8*10 -11 and 1.2*10, respectively -12 curie/l.

Bibliography: Borisov V.P. et al. Urgent Care for acute radiation impacts, M., 1976; Buldakov L. A. and Moskalev Yu. I. Problems of distribution and experimental evaluation permissible levels Cs137, Sr90 and Ru106, M., 1968, bibliogr.; Voinar A.I. Biological role of microelements in the body of animals and humans, p. 46, M., 1960; Ilyin JI. A. and Ivannikov A. T. Radioactive substances and wounds, M., 1979; K and with and in fi-na B. S. and T o r b e n k about V. P. Life of bone tissue, M., 1979; JI e in and V. I. Obtaining radioactive drugs, M., 1972; Metabolism of strontium, ed. J. M. A. Lenihen et al., trans. from English, M., 1971; Poluektov N. S. et al. Analytical chemistry of strontium, M., 1978; P e m and G. Course of inorganic chemistry, trans. from German, vol. 1, M., 1972; Protection of the patient in radionuclide investigations, Oxford, 1969, bibliogr.; Table of isotopes, ed. by S. M. Lederer a. V. S. Shirley, N. Y. a. o., 1978.

A. V. Babkov, Yu. I. Moskalev (rad.).

Strontium

STRONTIUM-I; m.[lat. strontium] Chemical element (Sr), a light silvery-white metal, radioactive isotopes of which are used in nuclear testing and technology.

◁ Strontium, oh, oh.

(lat. Strontium), a chemical element of group II of the periodic table, belongs to the alkaline earth metals. Named after the mineral strontianite, found near the village of Strontian in Scotland. Silver-white metal; density 2.63 g/cm 3, t mp 768°C. It is chemically very active, so the metal itself is used little (in the smelting of copper and bronze for their purification, in electric vacuum technology as a getter), salt is used in the production of paints, luminous compositions, glazes and enamels. SrTiO 3 is ferroelectric. During nuclear explosions in nuclear reactors, the radioactive isotope 90 Sr is formed (half-life 29.1 years), which poses a great danger to humans if it enters the natural environment.

STRONTIUM (lat. Strontium, from the village of Strontian in Scotland, near which it was found), a chemical element with atomic number 38, atomic mass 87.62. The chemical symbol is Sr, read "strontium". Located in the 5th period in group IIA of the periodic table of elements. Alkaline earth metal. Natural strontium consists of four stable isotopes with mass numbers 84 (0.56% by mass), 86 (9.86%), 87 (7.02%), and 88 (82.56%).
Outer electron layer configuration 5 s 2 . Oxidation state +2 (valency II). Atomic radius 0.215 nm, Sr 2+ ion radius 0.132 nm (coordination number 6). The sequential ionization energies are 5.6941 and 11.0302 eV. Electronegativity according to Pauling (cm. PAULING Linus) 1,0.
Strontium is a soft, silvery-white, relatively lightweight metal.
History of discovery
In 1764, a new mineral, strontianite, was discovered in a lead mine. In 1890, the Englishman A. Crawford and, at the same time, the Englishman T. Hope, German chemist (cm. M. Klaproth KLAPROT Martin Heinrich) (cm. and Russian academician T. E. Lovitz LOVITZ Toviy Egorovich) (cm. The oxide of a new element was isolated from strontianite. In 1808, the English chemist G. Davy obtained strontium amalgam.
DAVY Humphrey)
Prevalence in nature (cm. Content in the earth's crust is 0.034% by weight. Not found in free form. Important minerals: strontianite STRONTIANITE) (cm. and celestine CELESTINE)
SrSO4. As an impurity, it is found in calcium minerals, for example, in fluorapatite 3Ca 3 (PO 4) 2 · CaF 2.
Receipt
The main source of raw materials for the production of strontium and its compounds - celestine SrSO 4 - is first reduced with coal under high heating:
SrSO 4 + 4С = SrS + 4СО (cm. Then strontium sulfide SrS with hydrochloric acid HYDROCHLORIC ACID) (cm. transferred to SrCl 2 and dehydrated. To obtain Sr, its chloride is reduced with magnesium MAGNESIUM)
in a hydrogen atmosphere:
SrCl 2 + Mg = MgCl 2 + Sr (cm. Strontium is also obtained by the reduction of SrO with aluminum ALUMINUM) (cm., silicon SILICON)
or ferrosilicon:
4SrO + 2Al = 3Sr + SrAl 2 O 4
Physical and chemical properties Strontium is a soft, silvery-white metal that comes in three forms. The a-modification with a cubic face-centered lattice of the Cu type is stable up to 231°C, A
= 0.6085 nm. At 231-623°C - b-modification with a hexagonal lattice, at 623°C to the melting point (768°C) - g-modification with a cubic body-centered lattice. Boiling point 1390°C, density 2.63 kg/dm3. Strontium is a malleable, ductile metal.
Strontium is chemically highly reactive. Standard electrode potential Sr 2+ /Sr - 2.89 V. (cm. At room temperature in air, strontium is covered with a film of SrO oxide and SrO 2 peroxide. When heated in air, it ignites. Interacting with halogens, HALOGEN) (cm. forms halides SrCl 2 and SrBr 2. When heated to 300-400°C, it reacts with hydrogen HYDROGEN)
5Sr + 2CO 2 = SrC 2 + 4SrO
, forming the hydride SrH 2. By heating strontium in a CO 2 atmosphere, we get:
Strontium reacts actively with water:
Sr + 2H 2 O = Sr(OH) 2 + H 2
When heated, strontium reacts with nitrogen, sulfur, selenium and other non-metals to form nitride Sr 3 N 2, sulfide SrS, selenide SrSe and so on.
Strontium oxide is basic and reacts with water to form hydroxide:
SrO + H 2 O = Sr(OH) 2
When interacting with acidic oxides, SrO forms salts:
Sr 2+ ions are colorless. SrCl 2 chloride, SrBr 2 bromide, SrI 2 iodide, Sr(NO 3) 2 nitrate are highly soluble in water and color the flame carmine red. Insoluble carbonate SrCO 3, sulfate SrSO 4, medium orthophosphate Sr 3 (PO 4) 2.
Application
Strontium is used as an alloying additive to alloys based on magnesium, aluminum, lead, nickel and copper. Strontium is part of getters. Strontium compounds are used in pyrotechnics, are part of luminescent materials, emissive coatings of radio tubes, and are used in the manufacture of glass.
Strontium titanate SrTiO 3 is used in the manufacture of dielectric antennas, piezoelements, small-sized nonlinear capacitors, and as sensors infrared radiation. 90 Sr preparations are used in radiation therapy for skin and some eye diseases.
Physiological action
Strontium compounds are toxic. If it enters the body, damage to bone tissue and liver is possible. The maximum permissible concentration of strontium in water is 8 mg/l, in air for hydroxide, nitrate and oxide 1 mg/m 3, for sulfate and phosphate 6 mg/m 3.
Problems 90 Sr
When nuclear charges explode or due to the leakage of radioactive waste, the radioactive isotope 90 Sr enters the environment. Forming hydrocarbonate Sr(HCO 3) 2, which is highly soluble in water, 90 Sr migrates into water, soil, plants and animal organisms.

encyclopedic Dictionary . 2009 .

See what “strontium” is in other dictionaries:

- (new lat.). Light metal yellow color, named after a village in Scotland, in the vicinity of which it was discovered for the first time; in combination with carbon dioxide it forms the mineral strontianite. Dictionary of foreign words included in the Russian language.... ... Dictionary of foreign words of the Russian language

Nuclide table General information Name, symbol Strontium 90, 90Sr Alternative names Radiostrontium Neutrons 52 Protons 38 Properties of the nuclide Atomic mass 8 ... Wikipedia

STRONTIUM- chem. element, symbol Sr (lat. Strontium), at. n. 38, at. m. 87.62; belongs to the alkaline earth metals, has a silvery White color, density 2630 kg/m3, tmelt = 768 °C. It is chemically very active, so it is rarely used in its pure form. They use... Big Polytechnic Encyclopedia

Chem. element II gr. periodic table, serial number 38, at. V. 87, 63; consists of 4 stable isotopes. The average isotopic composition of ordinary S. is as follows: Sr84 0.56%, Si86 9.86%, Sr87 7.02%, Sr88 82.56%. One of the isotopes C. Sr87... ... Geological encyclopedia

Celestine Dictionary of Russian synonyms. strontium noun, number of synonyms: 5 foreigner (23) metal... Synonym dictionary

- (Strontium), Sr, chemical element of group II of the periodic system, atomic number 38, atomic mass 87.62; soft alkaline earth metal. As a result nuclear tests, accidents at nuclear power plants and radioactive waste enters the environment... ... Modern encyclopedia

- (lat. Strontium) Sr, a chemical element of group II of the periodic table, atomic number 38, atomic weight 87.62, belongs to the alkaline earth metals. Named after the mineral strontianite, found near the village of Strontian in Scotland.… … Big Encyclopedic Dictionary- (Strontium), Sr, chemical. element of group II periodic. systems of elements, at. number 38, at. mass 87.62, alkaline earth metal. Natural S. is a mixture of stable 84Sr, 86Sr, 88Sr, in which 88Sr predominates (82.58%), and 84Sr is the least (0.56%).... ... Physical encyclopedia