Cesium (English spelling and IUPAC spelling) or cesium (American spelling) is a chemical element with the symbols Cs and atomic number 55. This is soft, alkali metal silvery-gold with a melting point of 28.5 ° C (83.3 ° F), which makes it one of only five liquid metal elements at or near room temperature. Cesium has physical and chemical properties similar to rubidium and potassium. The most reactive of all metals, is pyrophoric and reacts with water even at -116 Â ° C (-177 Â ° F). It is the smallest electronegative element, with a value of 0.79 on the Pauling scale. It has only one stable isotope, cesium-133. Cesium is mostly mined from pollucite, whereas radioisotopes, particularly cesium-137, are fission products, extracted from waste generated by nuclear reactors.
German chemist Robert Bunsen and physicist Gustav Kirchhoff discovered cesium in 1860 with a newly developed fire spectroscopy method. The first small-scale application for cesium was as a "takeout" in vacuum tubes and photoelectric cells. In 1967, acting on Einstein's evidence that the speed of light is the most constant dimension in the universe, the International System of Units uses two specific wave quantities of the cesium-133 emission spectrum to determine the joints of seconds and meters. Since then, cesium has been widely used in very accurate atomic clocks.
Since the 1990s, the largest application of the element has been as a cesium format for drilling fluid, but has a wide range of applications in the production of electricity, electronics, and chemistry. The radioactive isotope of cesium-137 has a half-life of about 30 years and is used in medical applications, industrial gauges, and hydrology. Non-radioactive cesium compounds are only slightly toxic, but the tendency of pure metals to react explosively with water means that cesium is considered a dangerous substance, and radioisotopes present significant health and ecological hazards in the environment.
Video Caesium
Characteristics
Physical properties
Cesium is the softest element (has a hardness of 0.2 Mohs). It is a very brittle pale metal, which darkens in the presence of a small amount of oxygen. When confronted with mineral oil (where the best is stored during transportation), it loses its metallic luster and takes on a dull, gray look. It has a melting point of 28.5 Â ° C (83.3 Â ° F), making it one of several liquid metal elements near room temperature. Mercury is the only elemental metal with a melting point known to be lower than cesium. In addition, the metal has a rather low boiling point, 641 Â ° C (1.186 Â ° F), the lowest of all metals other than mercury. The compound burns in blue or purple.
Cesium forms alloys with other alkali metals, gold, and mercury (amalgam). At temperatures below 650 ° C (1.202 ° F), it is not alloyed with cobalt, iron, molybdenum, nickel, platinum, tantalum, or tungsten. It forms a well-defined intermetallic compound with antimony, gallium, indium, and thorium, which are photosensitive. This mixes with all other alkali metals (except lithium); alloys with a molar distribution of 41% cesium, 47% potassium, and 12% sodium have the lowest melting point of any known metal alloy, at -78 ° C (-108 ° F). Some amalgam have been studied: CsHg
2 black with purple metallic luster, while CsHg is golden, also with metallic luster.
The color of cesium gold comes from the decrease in the frequency of light required to stimulate electrons from the alkali metals as the inherited group. For lithium via rubidium, this frequency is in ultraviolet, but for cesium it enters the edge of the blue-violet spectrum; in other words, the plasmonic frequency of the alkali metal becomes lower than lithium to cesium. So cesium transmits and absorbs some special violet light while other colors (have a lower frequency) are reflected; because it looks yellowish.
Chemical Properties
Cesium metal is highly reactive and highly pyrophoric. It burns spontaneously in the air, and reacts explosively with water even at low temperatures, more than any other alkali metal (the first group of the periodic table). It reacts with solid water at temperatures as low as -116 ° C (-177 ° F). Due to this high reactivity, cesium metal is classified as a hazardous material. These are stored and delivered in saturated and dry hydrocarbons such as mineral oil. This can be handled only under inert gas, such as argon. However, cesium water explosions are often less powerful than sodium-water explosions with equal amounts of sodium. This is because cesium instantly explodes when in contact with water, leaving little time for hydrogen to accumulate. Cesium can be stored in a vacuum-sealed borosilicate glass ampule. In amounts greater than about 100 grams (3.5 oz), cesium is delivered in a sealed stainless steel container.
Chemical cesium is similar to other alkali metals, especially rubidium, the element above cesium in the periodic table. As expected for alkali metals, the only common oxidation is 1. Some minor differences arise from the fact that it has a higher atomic mass and is more electropositive than other alkali (nonradioactive) metals. Cesium is the most electropositive chemical element. Cesium ions are also larger and less "hard" compared to lighter alkaline metals.
​​Compound
Most of the cesium compounds contain elements as cations Cs , which binds ionically to various anions. One notable exception is an anion caeside ( Cs -
), and the other is some suboxide (see section on oxide below).
Salt Cs is usually colorless unless the anion itself is colored. Many of the simple salts are hygroscopic, but less of the salts corresponding to lighter alkali metals. Phosphates, acetates, carbonates, halides, oxides, nitrates, and water-soluble sulfate salts. The double salt is often less soluble, and the low solubility of cesium aluminum sulfate is exploited in perfecting the Cs of the ore. Double salt with antimony (like CsSbCl
4 ), bismuth, cadmium, copper, iron, and tin are also not well dissolved.
Cesium hydroxide (CsOH) is hygroscopic and very basic. This quickly etches the semiconductor surface like silicon. CsOH has previously been considered by chemists as the "strongest base", reflecting relatively weak attraction between Cs and OH - ions; it is indeed the strongest base of Arrhenius, but a number of water-insoluble compounds, such as n -butyllithium and sodium amide, are more basic.
The stoichiometric mixture of cesium and gold will react to form cesium yellow auride (Cs Au - ) during heating. Anion auride here behaves as a pseudohalogen. The compound reacts violently with water, producing cesium hydroxide, metallic gold, and hydrogen gas; in liquid ammonia can be reacted with a special ion-exchange resin of cesium to produce tetramethylammonium auride. The platinum analog compound, red cesium platinide (Cs 2 Pt), contains platinum ions that behave as pseudochalcogen.
Complex
Like all metal cations, Cs forms complexes with Lewis bases in solution. Because of their large size, Cs usually adopts a coordination number greater than 6, a number typical for smaller alkali metal cations. This difference is seen in 8-coordinate CsCl. The amount of high coordination and tenderness (the tendency to form covalent bonds) is an exploited property in separating Cs from other cations in remediation of nuclear waste, where 137 Cs must be separated from a large number of nonradioactive K .
Halide
Cesium fluoride (CsF) is a hygroscopic white solid widely used in organofluorine chemistry as an anion fluoride source. Cesium fluoride has a halit structure, which means that the packs of Cs and F - in the closest cubic arrangement are packed as well as Na and Cl - in sodium chloride. In particular, cesium and fluorine have the lowest and highest electronegativity, respectively, among all known elements.
Cesium chloride (CsCl) crystallizes in a simple cubic crystal system. Also called "cesium chloride structure", this structural motive consists of a primitive cubic lattice with a base of two atoms, each with an eightfold coordination; The chloride atom lies on the lattice points at the edge of the cube, while the cesium atom is located in the hole in the center of the cube. This structure is divided by CsBr and CsI, and many other compounds that do not contain Cs. By contrast, most alkaline halides have sodium chloride (NaCl) structures. The structure of CsCl is preferred because Cs has ionic radius of 174Ã, pm and Cl -
181Ã, pm.
Oxide
More than other alkali metals, cesium forms many binary compounds with oxygen. When cesium burns in the air, superoxide CsO
2 is the main product. The "normal" cesium oxide ( Cs
2 O ) forms a yellow-orange hexagonal crystal, and is the only oxide of anti- CdCl
2 type. It evaporates at 250 Ã, Â ° C (482 Ã, Â ° F), and decomposes into cesium metal and peroxide Cs
2 < at temperatures above 400 Â ° C (752 Â ° F). In addition to superoxide and ozonide CsO
3 , some brightly colored sub-oxides have also been studied. This includes Cs
7 O , Cs
4 O , Cs
11 O
3 , Cs
3 O (dark-green), CsO, Cs > 3 O
2 , and Cs
7 O
2 The latter may be heated in a vacuum to produce Cs
2 O Binary compounds with sulfur, selenium, and tellurium are also present. Isotope
Cesium has 39 known isotopes, ranging in mass amounts (ie the number of nucleons in a nucleus) from 112 to 151. Some are synthesized from the light elements by slow neutrons capture (S-process) in old stars and by -process in supernova explosion. The only stable isotope cesium is 133 Cs, with 78 neutrons. Despite having a large nuclear spin ( 7 2 ), nuclear magnetic resonance studies can use this isotope. at 11.7 MHz resonant frequency.
The radioactive 135 Cs has a very long beak of about 2.3 million years, the longest of all the radioactive isotopes of cesium. 137 Cs and 134 Cs has a half-life of 30 and two years, respectively. 137 Cs decomposes to be short-lived 137m Ba by beta decay, and then becomes barium nonradioactive, while 134 Cs changes to 134 Ba directly. Isotopes with mass amounts of 129, 131, 132 and 136, have half-lives between one day and two weeks, while most of the other isotopes have a half-life of a few seconds to a fraction of a second. There are at least 21 metastable nuclear isomers. In addition to 134m Cs (with half-life just under 3 hours), all very unstable and decomposed with half-life of few minutes or less.
Isotope 135 Cs is one of the long-lived fission products of uranium produced in nuclear reactors. However, the product of this fission product is reduced in most reactors because its predecessor, 135 Xe, is a potent neutron toxin and often moves to stable 136 Xe before it can decompose into 135 Cs.
Beta decay from 137 Cs to 137m Ba is a strong emission of gamma radiation. 137 Sr is the main product of nuclear fission, and a major source of radioactivity from spent fuel after several years of cooling, lasting several hundred years. Both isotopes are the largest residual radioactive source in the Chernobyl disaster area. Due to the low capture rate, removing 137 Cs via improper neutron capture and the only solution currently allowed to rot over time.
Almost all of the cesium produced from nuclear fission comes from beta decay from the richer neutron fission products, passing through the various isotopes of iodine and xenon. Because iodine and xenon are volatile and can diffuse through nuclear or air fuel, radioactive cesium is often made away from the original fission site. With nuclear weapons testing in the 1950s to the 1980s, 137 Cs was released into the atmosphere and returned to the surface of the earth as a component of radioactive fallout. This is a ready marker of the movement of soil and sediment from that period.
Genesis
Cesium is a relatively rare element estimated at an average of 3 parts per million in Earth's crust. This is the 45th and 36th most abundant element of metals. However, it is more abundant than elements such as antimony, cadmium, lead, and tungsten, and two fold more abundant than mercury and silver; it's 3,3% abundant like rubidium, which is closely related, chemically.
Because of its large ionic radius, cesium is one of the "incompatible elements". During crystallization of the magma, cesium is concentrated in the liquid phase and crystallizes the latter. Therefore, the largest deposit of cesium is the pegmatite ore zone formed by this enrichment process. Because cesium does not replace potassium as easily as rubidium, alkaline evaporite mineral sylvite (KCl) and carnalite ( KMgCl
3 Ã, Â · 6H
2 O ) may contain only 0.002% cesium. As a result, Cs is found in some minerals. Percentage of cesium number can be found in beryl ( Be
3 Al
2 (SiO
3 )
6 ) and avogadrite ( (K, Cs) BF
4 ), up to 15% wt% Cs 2 O in mineral pezzottaite which is closely related (Cs (Be 2 Li) Al 2 6 O 18 ), up to 8.4 % weight Cs 2 O in rare londonite minerals ( (Cs, K) Al
4 Be
4 (B, Be)
12 O
28 ), and less in the wider rhodizite The only economically important ore for cesium is pollucite Cs (AlSi 2 O
6 ) , found in several places around the world in pegmatites categorized, associated with more lithium minerals commercially important, lepidolite and petalite.Inside pegmatites, large grain size and strong mineral separation produce high grade ore for mining.
One of the most significant and richest sources of cesium in the world is the Tanco Mine at Bernic Lake in Manitoba, Canada, which is estimated to contain 350,000 metric tons of pollucite ore, representing more than two-thirds of the world's reserve base. Although the stoichiometric content of cesium in the pollucite is 42.6%, the pure pollucite sample of this deposit contains only about 34% cesium, while the content averages 24% by weight. Commercial pollucite contains more than 19% cesium. The Bikita pegmatite deposit in Zimbabwe is mined for its petalit, but also contains large amounts of pollucite. Another well-known pollucite source is in the Karibib Desert, Namibia. With the current world production rate of 5 to 10 metric tons per year, the reserves will last for thousands of years.
Maps Caesium
Production
Mining and refining of pollucite ore is a selective process and is carried out on a smaller scale than most other metals. The ore is crushed, sorted, but not usually concentrated, and then ground. Cesium is then extracted from pollucite mainly by three methods: acid digestion, alkaline decomposition, and direct reduction.
In acid digestion, silicate pollucite rocks are dissolved with strong acids, such as hydrochloric (HCl), sulfuric ( H
2 SO
4 ), hydrobromic (HBr), or hydrofluoric (HF) acids. With hydrochloric acid, the dissolved chloride mixture was produced, and the insoluble chloride double salt of cesium was precipitated as cesium antimony chloride ( Cs
4 SbCl
7 ), cesium iodine chloride ( Cs
2 ICl ), or cesium hexachlorocerate ( Cs
2 (CeCl
6 ) ). After separation, pure precipitated salts are described, and pure CsCl is precipitated by evaporation of water.
The sulfuric acid method produces double insoluble salt directly as cesium alum ( CsAl (SO
4 )
2
2 O ). The aluminum sulphate component is converted into insoluble aluminum oxide by alum baking with carbon, and the resulting product is washed with water to produce Cs
2 SO
4 solution.
Baking pollucite with calcium carbonate and calcium chloride produces insoluble calcium silicate and dissolved cesium chloride. Leaching with water or dilute ammonia ( NH
4 OH ) produces a dilute chloride solution (CsCl). This solution can be evaporated to produce cesium chloride or converted into alum cesium or cesium carbonate. Although not commercially feasible, ore can be directly reduced by potassium, sodium, or calcium in a vacuum can produce metal cesium directly.
Most of the mined cesium (such as salt) is directly converted to cesium format (HCOO - Cs ) for applications such as oil drilling. To supply the growing market, Cabot Corporation built a production plant in 1997 at the Tanco mine near Bernic Lake in Manitoba, with a capacity of 12,000 barrels (1,900 m 3 ) per year of cesium formation solution. The major small-scale commercial compounds of cesium are cesium chloride and nitrate.
Alternatively, cesium metal may be obtained from purified compounds derived from ores. Cesium chloride and other cesium halides can be reduced at 700 to 800 ° C (1,292 to 1,472 ° F) with calcium or barium, and the cesium metal is distilled from the results. In the same way, aluminate, carbonate, or hydroxide can be reduced by magnesium.
This metal can also be isolated by electrolysis of fused cesium cyanide (CsCN). Extremely pure and gaseous cesium can be produced with hot decomposition of 390Ã, Â ° C (734Ã, Â ° F) of cesium azide CsN
3 , which can result from dilute cesium sulfate and barium azide. In a vacuum application, cesium dichromate can be reacted with zirconium to produce pure cesium metal without other gaseous products.
- Cs
2 Cr < span>
2 O
7 2 Zr -> 2 Cs 2 ZrO
2 < span> Cr
2 O
< sub style = "font-size: inherit; line-height: inherit; vertical-align: baseline"> 3
The price of 99.8% pure cesium (base metal) in 2009 was about US $ 10 per gram ($ 280 per ounce), but the compounds were significantly cheaper.
History
In 1860, Robert Bunsen and Gustav Kirchhoff discovered cesium in mineral water from DÃÆ'¼rkheim, Germany. Because of the bright blue lines in the emission spectrum, they derive the name from the Latin word caesius, meaning sky-blue. Cesium was the first element found with spectroscopes, which Bunsen and Kirchhoff had discovered only a year earlier.
To obtain a pure cesium sample, 44,000 liters (9.700Ã, Â ° imp, gal, 12,000 US gal) of mineral water should be evaporated to produce 240 kilograms (530 lb) of concentrated salt solution. Alkaline earth metal is deposited either as sulfate or oxalate, leaving the alkali metal in solution. After conversion to nitrate and extraction with ethanol, a sodium-free mixture was obtained. From this mixture, lithium is precipitated by ammonium carbonate. Potassium, rubidium, and cesium form insoluble salts with chloroplatinic acid, but they show little difference in dissolution in hot water, and less soluble cesium and rubidium hexachloroplatinate ((Cs, Rb) 2 PtCl 6 ) obtained by fractional crystallization. After reduction of hexachloroplatinate with hydrogen, cesium and rubidium are separated by differences in their carbonate solubility in alcohols. This process yielded 9.2 grams (0.32 oz) of rubidium chloride and 7.3 grams (0.26 oz) of cesium chloride from the initial 44,000 liters of mineral water.
From cesium chloride, the two scientists estimate the weight of the new element at 123.35 (compared to what is now accepted 132.9). They tried to produce cesium elements by electrolysis of liquid cesium chloride, but instead of metal, they obtained a blue homogeneous substance that "either under the naked eye or under a microscope showing the slightest trace of metal"; as a result, they assign it as subchloride ( Cs
2 Cl ). In fact, the product may be a mixture of colloidal metals and cesium chloride. Electrolysis of an aqueous chloride solution with a mercury cathode produces a cesium amalgam that readily decomposes under aqueous conditions. The pure metal was eventually isolated by German chemist Carl Setterberg while working on his doctorate with KekulÃÆ'Â © and Bunsen. In 1882, he produced cesium metal with cesium cyanide electrolysis, avoiding problems with chloride.
Historically, the most important use for cesium has been in research and development, especially in the fields of chemistry and electricity. Very few applications existed for cesium until the 1920s, when it began to be used in radio vacuum tubes, where it had two functions; as the taker, it removed excess oxygen after manufacture, and as the coating on the cathode was heated, it increased the electrical conductivity. Cesium was not recognized as a high-performance industry metal until the 1950s. Applications for nonradioactive cesium include photoelectric cells, photomultiplier tubes, optical components of infrared spectrophotometers, catalysts for several organic reactions, crystals for sparkle counters, and in magnetohydrodynamic power plants. Cesium is also, and is still used as a positive ion source in secondary ion mass spectrometry (SIMS).
Since 1967, the International Measurement System has based the main time unit, the second, on the properties of cesium. The International Unit System (SI) defines the second as the duration of 9192.631.770 cycles at the microwave frequency of the spectral line corresponding to the transition between two levels of hyperfin energy from the cesium-133 base state. The 13th General Conference on Weight and Size of 1967 establishes the second as: "the duration of 9192.631.770 microwave light cycle absorbed or emitted by the hyperfine transition of cesium-133 atoms in their ground state is not disturbed by external fields".
Apps
Petroleum exploration
The current greatest use of nonradioactive cesium is in cesium formate fluid drilling for the extractive oil industry. The aqueous solution of cesium formate (HCOO - Cs ) - made by reacting cesium hydroxide with formic acid - was developed in the mid-1990s for use as an oil well drilling and solution fluid. The function of the drilling fluid is to lubricate the drill bit, to bring the piece of rock to the surface, and to maintain pressure on the formation during drilling the well. Complementary fluid helps the placement of control hardware after drilling but before production by maintaining pressure.
The high density of cine formate brine (up to 2.3 g/cm 3 , or 19.2 pounds per gallon), coupled with the relatively benign nature of most cesium compounds, reduces the need for high toxicity. suspended solids density in drilling fluids - significant technological, engineering and environmental advantages. Unlike many other heavy liquid components, cesium formats are relatively environmentally friendly. Cesium reformat saltwater can be mixed with potassium and sodium formation to decrease the density of liquid to water (1.0 g/cm 3 , or 8.3 pounds per gallon). In addition, it is biodegradable and can be recycled, which is important given the high cost (about $ 4,000 per barrel in 2001). Alkaline formate is safe to handle and does not damage production formations or downhole metals as an alternative to corrosive, high-density brines (such as zinc bromide ZnBr
2 solution) is sometimes done; they also require less cleaning and reduced disposal costs.
atomic clock
The cesium-based atomic clock uses the electromagnetic transition in the cesium-133 atomic hyperfine structure as a reference point. The first accurate cesium clock was built by Louis Essen in 1955 at the National Physical Laboratory in England. The cesium clock has increased over the past half century and is considered the "most accurate realization of the unit that mankind has yet to achieve". This clock measures the frequency with errors of 2 to 3 parts in 10 14 , which corresponds to an accuracy of 2 nanoseconds per day, or one second in 1.4 million years. The latest version is more accurate than 1 part in 10 15 , about 1 second in 20 million years. The Cesium standard is the main standard for standard time and frequency measurements. The cesium clock sets the time of the mobile phone network and the Internet.
Electric and electronic
The caesium steam thermionic generator is a low-power device that converts heat energy into electrical energy. In a two-electrode vacuum converter, cesium neutralizes the charge space near the cathode and increases the current flow.
Cesium is also important for its photoemissivenya properties, converting light into electron flow. It is used in photoelectric cells due to cesium-based cathodes, such as intermetallic compounds K
2 CsSb , has a low threshold voltage for electron emission. The range of photoemissive devices using cesium includes optical character recognition devices, photomultiplier tubes, and video camera tubes. However, germanium, rubidium, selenium, silicon, tellurium, and some other elements may be replaced by cesium in the photosensitive material.
Cesium iodide (CsI), bromide (CsBr) and cesium fluoride (CsF) crystals used for scintillators at luster counters are widely used in mineral exploration and particle physics research to detect gamma and X-ray radiation. Being a heavy element, cesium provides good stopping power with better detection. The cesium compound can provide a faster response (CsF) and less hygroscopic (CsI).
Cesium vapor is used in many common magnetometers.
This element is used as an internal standard in spectrophotometry. Like other alkali metals, cesium has a great affinity for oxygen and is used as a "take" in vacuum tubes. Other uses of metal include high-energy lasers, steam lights, and steam rectifiers.
Centrifugation of fluid
The high density of cesium ions makes the solution of cesium chloride, cesium sulfate, and cesium trifluoroacetate ( Cs (O
2 CCF
3 ) ) is useful in molecular biology for density gradient ultracentrifugation. This technology is used primarily in isolation of virus particles, organelles and subcellular fractions, and nucleic acids from biological samples.
Chemical and medical uses
Relatively few chemical applications use cesium. Doping with cesium compounds increases the effectiveness of some metal-ionic catalysts for chemical synthesis, such as acrylic acid, anthraquinone, ethylene oxide, methanol, phthalal anhydride, styrene, methyl methacrylate monomers, and various olefins. It is also used in catalytic conversion of sulfur dioxide into sulfur trioxide in the production of sulfuric acid.
Cesium fluoride enjoys the use of a niche in organic chemistry as a base and as a source of anhydrous fluoride ions. Cesium salts sometimes replace potassium or sodium salts in organic synthesis, such as cyclization, esterification, and polymerization. Cesium has also been used in the thermoluminescent (TLD) dosimeter : When exposed to radiation, it obtains a crystal defect which, when heated, returns with a light emission proportional to the dose received. Thus, measuring the light pulse with a photomultiplier tube may allow the accumulation of the radiation dose to be measured.
Nuclear and isotope applications
Cesium-137 is a radioisotope commonly used as a gamma-emitter in industrial applications. Its profits include a half-life of about 30 years, its availability from the nuclear fuel cycle, and has 137 Ba as a stable end product. High water solubility is a disadvantage that makes it incompatible with large pond irradiators for food and medical supplies. It has been used in agriculture, cancer treatment, and food sterilization, sewage sludge, and surgical equipment. The radioactive isotope of cesium in radiation devices is used in the medical field to treat certain types of cancer, but the emergence of better alternatives and the use of water-soluble cesium chloride at the source, which can create widespread contamination, gradually puts some of these cesium sources unused. Cesium-137 has been used in various industrial measuring instruments, including moisture, density, leveling, and thickness gauge. It has also been used in well logging devices to measure electron densities of rock formations, analogous to the bulk density of formations.
Cesium-137 has been used in hydrological studies analogous to those with tritium. As a daughter product of fission bomb testing from the 1950s through the mid-1980s, cesium-137 was released into the atmosphere, where it was absorbed easily into solution. The year-to-year variations known in the period allow for correlation with soil layers and sediments. Cesium-134, and to a lesser extent cesium-135, has also been used in hydrology to measure cesium output by the nuclear power industry. Although they are less common than cesium-133 or cesium-137, these bamboo isotopes are produced only from anthropogenic sources.
Other uses
Cesium and mercury are used as propellants in early ion engines designed for the propulsion of spacecraft on very long interplanetary or extraplanet missions. The fuel is ionized by contact with a charged tungsten electrode. However corrosion by cesium in spacecraft components has led to the development of inert gas propellant propellers, such as xenon, which are easier to handle in ground-based testing and do little potential damage to the spacecraft. Xenon was used in the experimental spacecraft Deep Space 1 which was launched in 1998. Nevertheless, the driving force of field propulsion power that speeds up liquid metal ions such as cesium has been built.
Cesium nitrate is used as an oxidizer and a pyrolyctic dye to burn silicon in infrared flares, such as the flame of LUU-19, because it emits a lot of light in the near infrared spectrum. Cesium is used to reduce radar signals from exhaust effluents on SR-71 Blackbird military aircraft. Cesium and rubidium have been added as carbonates to the glass as they reduce electrical conductivity and improve the stability and durability of optical fibers and night vision devices. Cesium fluoride or cesium aluminum fluoride is used in fluxes formulated for aluminum brazing alloys containing magnesium.
Magnetohydrodynamic power systems (MHD) were studied, but failed to gain widespread acceptance. Cesium metal has also been considered a working fluid in the high temperature Rankine turboelectric generator cycle.
Cesium salts have been evaluated as an antiishock reagent after administration of arsenic drugs. Because of its effect on the heart rhythm, however, they are less used than potassium or rubidium salts. They have also been used to treat epilepsy.
Cesium-133 can be laser cooled and used to investigate underlying problems and technologies in quantum physics. It has a very convenient Feshbach spectrum to allow the study of the ultracold atoms requiring a melodious interaction.
Health and safety hazards
Non-radioactive cesium compounds are only slightly toxic and nonradioactive cesium is not a significant environmental hazard. Because the biochemical process can confuse and replace cesium with potassium, excess cesium can cause hypokalemia, arrhythmias, and acute heart attacks. But such numbers are not usually found in natural resources.
The median lethal dose (LD 50 ) for cesium chloride in rats was 2.3 g per kilogram, which is proportional to LD 50 potassium chloride and sodium chloride. The main use of nonradioactive cesium, such as cesium formats in petroleum drilling fluids because it is much more toxic than an alternative, though more expensive.
The cesium metal is one of the most reactive and highly explosive elements in the water. The hydrogen gas produced by the reaction is heated by the heat energy released at the same time, causing ignition and a loud explosion. This can happen with other alkali metals, but cesium is so strong that this explosive reaction can be triggered even by cold water.
It's very pyrophoric: the cesium autoignition temperature is -116Ã, Â ° C, and it's explosive trigger in the air to form cesium hydroxide and various oxides. Cesium hydroxide is a very strong base, and will quickly damage the glass.
Isotopes 134 and 137 are present in the biosphere in small amounts of human activity, differ by their location. Radiocaesium does not accumulate in the body just as easily as other fission products (such as radioiodine and radiostrontium). About 10% of radiocaesium is absorbed out of the body relatively quickly in sweat and urine. The remaining 90% have biological half-life between 50 and 150 days. Radiocaesium follows potassium and tends to accumulate in plant tissues, including fruits and vegetables. Plants vary greatly in cesium absorption, sometimes showing great resistance to it. It is also well documented that fungi from contaminated forests collect radiocaesium (cesium-137) in mushroom sporokarps. The accumulation of cesium-137 in the lake has been a major concern after the Chernobyl disaster. Experiments with dogs showed that a single dose of 3.8 millicuries (140 MBq, 4.1Ã,® G caesium-137) per kilogram was lethal in three weeks; Smaller amounts can cause infertility and cancer. The International Atomic Energy Agency and other sources have warned that radioactive materials, such as cesium-137, can be used in radiological dispersal equipment, or "dirty bombs".
See also
- GoiÃÆ' Â ¢ nia accident, a major radioactive contamination incident in 1987 involving Cesium-137.
- Kramatorsk radiological accident, another Cs137 incident between 1980-1989.
- Acerinox Accident, Cesium-137 contamination accident in 1998.
Note
References
External links
- Cesium or Cesium in Periodic Video Table (University of Nottingham)
- See Cesium reaction (the most reactive metal in the periodic table) with the Fluorine (most reactive non-metallic) facility of the Royal Institution.
- Andrey Yu. Rogachev, Mao-sheng Miao, Gabriel Merino, et al . CsF Molecule 5 and CsF 2 . Angewandte Chemie, 2015. 127 (28).doi: 10.1002/ange.201500402
Source of the article : Wikipedia
0 Comments