The characteristics of cesium, its structural and quality features inherent in this element, must pass in chemistry. Not only schoolchildren, but also students of chemical specialties should know the specific features of this compound. The use of cesium is currently quite wide - but in a specific field. This is largely due to the fact that at room temperature the element acquires a liquid state, but practically does not occur in its pure form. Currently, only five metals have similar qualities. The properties of cesium determine the interest in it of scientists and the possibilities for using the compound.
What is it about?
Soft cesium metal is indicated in the periodic table by the symbols Cs. Its serial number is 55. The soft metal has a silver, golden hue. Melting point - 28 degrees Celsius.
Cesium is an alkali metal whose qualities and characteristics are similar to potassium, rubidium. The structure of cesium causes increased reactivity. The metal can react with water at a temperature on the Celsius scale of 116 degrees below zero. The chemical element cesium has a high pyrophoricity. It is obtained from pollucite. Many radioactive isotopes of cesium (including those that have found active use of cesium 137) are produced during the processing of waste arising from the operation of a nuclear reactor. Cesium 137 is the result of a cleavage reaction.
Historical background
The merit of the discovery of the electronic formula of cesium belongs to chemists from Germany, outstanding minds in their field, Kirchhoff, Bunsen. This event happened back in 1860. At that time, they began to actively change the newly invented method of flame spectroscopy, and in the course of their experiments, German scientists discovered a previously unknown chemical element - cesium. At that time, cesium was presented as a recipient, which is important for photocells, electronic lamps.
Noticeable changes in the history of the definition and separation of an element occurred in 1967. Taking into account the statement made by Einstein that the speed of light can be considered the most constant measurement factor inherent in our universe, it was decided to isolate cesium 133. This was an important point in expanding the spectrum of application of the chemical element of cesium - in particular, atomic clocks are made on it.
Cesium in the nineties
It was in the last decade of the last century that the chemical element cesium began to be used especially actively by mankind. It turned out that it is applicable in the work of drilling fluids. It was also possible to find a fairly extensive area of application in the chemical industries. It turned out that cesium chloride and its other derivatives can be used in the construction of complex electronics.
Then, in the nineties, the special attention of the scientific community was riveted to everything that could become a new word in nuclear, nuclear energy. It was then that the most thoroughly studied radioactive cesium. It was revealed that the half-life of this component requires about three decades. Currently, radioactive isotopes of cesium are widely used in hydrology. Medicine and industry are not without them. The most widespread is the radioactive isotope of cesium 137. Cesium is characterized by a low level of toxic abilities, while at the same time, radioactive derivatives in high concentrations can harm nature and humans.
Physical parameters
The specificity of cesium (as well as cesium chloride and other derivatives of this metal) makes it possible to widely use the product. Among other elements, it is cesium that has the smallest hardness indicator - only 0.2 units on the Mohs scale. In addition to softness, pliability is also characteristic of metal. In the normal state, the correct electronic formula of cesium allows the formation of a pale-colored material capable of changing the paint to a darker one at the slightest contact with oxygen compounds.
The melting point of the metal is only 28 degrees Celsius, which means that the compound is one of five metals at room temperature or close to that in the liquid phase. An even lower melting point than cesium is recorded only in mercury. The boiling point of cesium is also small - only mercury is less. Features of the electrochemical potential regulate the combustion of the metal - it creates violet shades or blue.
Compatibility and features
Cesium has the ability to react with alkaline compounds, metals. The element also forms cesium oxides. In addition, there are reactions with mercury mixtures, gold. Features of interaction with other compounds, as well as temperature conditions under which reactions are possible, declare possible intermetallic compounds. In particular, cesium is the starting component for the formation of photosensitive compounds. For this, a metal reaction is carried out with the participation of thorium, antimony, gallium, indium.
In addition to cesium oxide, chemists are also interested in the results of interaction with a number of alkaline elements. At the same time, it must be borne in mind that the metal cannot react with lithium. Each of the cesium alloys is characterized by its own shade. Some mixtures are black-violet compounds, others are painted in a golden hue, and others are almost colorless, but with a pronounced metallic sheen.
Chemical features
The most pronounced feature of cesium is its pyrophoricity. In addition, the electrochemical potential of the metal attracts the attention of scientists. Cesium can spontaneously catch fire right in the air. Explosion occurs when interacting with water, even if reaction conditions suggested low temperatures. In this regard, cesium differs markedly from the first group of the Mendeleev chemical table. In the interaction of cesium and water in solid form, a reaction also occurs.
It was revealed that the half-life of cesium lasts about three decades. The material was recognized as hazardous due to its characteristics. To work with cesium, an inert gas atmosphere must be created. At the same time, an explosion in contact with water with an equal amount of sodium and cesium in the second case will be significantly weaker. Chemists explain this by the following feature: upon contact of cesium with water, an instant explosive reaction occurs, that is, there is not enough long time gap for hydrogen accumulation. The best storage method for cesium is corked containers made of borosilicate compound.
Cesium: as part of compounds
Cesium in the compounds acts as a cation. There are many diverse anions with which a compound formation reaction is possible. Most cesium salts are colorless unless staining is due to anion. Simple salts are hygroscopic, although to a lesser extent than other light alkali metals. Many are dissolved in water.
Double salts have a relatively low degree of solubility. This has found quite wide application in industry. For example, aluminum-cesium sulfate is actively used in ore refineries due to its low solubility with water.
Cesium: unique and useful
Visually, this metal is similar to gold, but slightly lighter than the most popular noble metal. If you take a piece of cesium in your hand, it will quickly melt, and the resulting substance will be mobile, it will slightly change color - closer to silver. In the molten state, cesium perfectly reflects the rays of light. Of alkali metals, cesium is considered the heaviest, while at the same time it has the lowest density.
The history of the discovery of cesium contains references to the Durheim source. It was from here that a sample of water was sent for laboratory research. During the analysis of the constituent components, special attention was paid to solving the question: which particular element provides the healing qualities of the fluid? The German scientist Bunsen decided to apply the method of spectral analysis. It was then that two unexpected lines of a blue hue appeared, which were not characteristic of the compounds known at that time. It is the color of these bands that helped scientists choose a name for the new component - sky blue in Latin sounds like “cesium”.
Where can I find you?
As was revealed during lengthy tests, cesium is a dispersed element, which is extremely rare under natural conditions. So, conducting a comparative analysis of the content of rubidium and cesium in the planet’s crust, scientists have found that the second is hundreds of times less. A rough estimate of the concentration gave an indicator of 7 * 10 (-4)%. No other less sensitive method than spectroscopy would simply allow the detection of such a rare compound. This explains the fact that before scientists did not even suspect the existence of cesium.
At present, it has been possible to find out that cesium is more often found in rocks extracted in the mountains. Its concentration in this material does not exceed thousandths of a percent. Categorically small quantities were recorded in the waters of the seas. The concentration level in lithium and potassium mineral compounds reaches up to tenths of a percent. Most often it can be detected in lepidolite.
So similar, but completely different
When comparing the distinctive features of cesium and rubidium, as well as other elements that are extremely rare, it was found that cesium is characterized by the formation of unique minerals, which other compounds are not capable of. This is how pollucyte, rhodicite, avogadrit are obtained.
Rhodicitis, as scientists have found, is extremely rare. Similarly, it is very difficult to find avogadrit. Pollucite is somewhat more common, in some cases small deposits were found. They have a very low power, but contain cesium in an amount of 20-35 percent of the total mass. The most important, from the point of view of the public, half-cells were found in the American bowels and in Russia. There are also Swedish developments, Kazakhstan. It is known that half-lucite is found in the south-west of the African continent.
Work continues
It is no secret that discovering an element and receiving it in its purest form are two completely different tasks, albeit related. When it became clear that cesium was very rare, scientists began to develop methods for synthesizing metal in the laboratory. At first, it seemed that this was an absolutely impossible task if we used the means and equipment available at that time. For many years, Bunsen was not able to isolate metallic cesium in its pure form. Only two decades later, advanced chemists were able to finally solve this problem.
The breakthrough occurred in 1882 when Setterberg from Sweden electrolyzed a mixture of four parts consisting of cesium cyanides, to which one part of barium was mixed. The latter component was used to make the melting point lower. Cyanides, as scientists already knew at that moment, were very dangerous components. At the same time, pollution was formed due to barium, which did not allow obtaining a more or less satisfactory amount of cesium. It was clear that the methodology required significant improvements. A good proposal in this area was submitted for discussion by the scientific community by Beketov. It was then that cesium hydroxide attracted attention. If you restore this compound by using metallic magnesium, increasing heat and using hydrogen current, you can achieve a slightly better result than that proved by the Swedish chemist. However, real experiments have shown that the yield is half as much as calculated in theory.
What's next?
Cesium remained the focus of attention of the international chemical scientific community. In particular, in his research, the French scientist Axpil devoted much effort and time to him. In 1911, he proposed a radically new approach to the extraction of pure cesium. It was necessary to carry out the reaction in a vacuum, metal chloride was taken as the starting material, and calcium metal was used to restore it.
Such a reaction, experiments have shown, occurs almost to the end. To achieve a sufficient effect, it is necessary to use a special device. In laboratories, they usually resort to refractory glass or use quartz containers. The device must have a process. Inside, a pressure of about 0.001 mm Hg is maintained. Art. For a successful reaction, it is necessary to provide heating of the tank to 675 degrees Celsius. In this case, cesium is released, which evaporates almost immediately. The pairs pass into the appendage intended for this. But potassium chloride mainly settles directly in the reactor. Under given conditions, the volatility of this salt is so small that it can be ignored altogether, since this compound has a characteristic melting point of 773 degrees (on the same Celsius scale). This means that the precipitate can melt if the tank is overheated by a hundred degrees relative to the intended one. To achieve the most effective result, it is necessary to conduct a second distillation process. To do this, create a vacuum. The output will be perfect metal cesium. Currently, the described technique is used most widely and is considered optimal for obtaining compounds.
Activity and reactions
In the course of numerous studies, scientists were able to determine that surprising activity is inherent in cesium, normally not characteristic of metals. On contact with air, a fire occurs that leads to the release of superoxide. You can achieve oxide if you limit the access of oxygen to the reagents. It is possible to form suboxides.
If cesium is in contact with phosphorus, sulfur, halogen, this provokes a reaction accompanied by an explosion. An explosion also accompanies a reaction with water. Using a mold, a glass, you may encounter the fact that the container literally shatters into pieces. A reaction with ice is also possible if the temperature on the Celsius scale is not lower than 116 degrees. As a result of this reaction, hydrogen and hydroxide are produced.
Hydroxide: features
In the course of studying the reaction products produced by cesium, chemists revealed that the resulting hydroxide is a very strong base. Interacting with it, it must be remembered that at high concentrations, this compound can easily destroy glass even without additional heating. But with an increase in temperature, hydroxide easily melts nickel, iron, cobalt. A similar effect will be on zirconium dioxide, corundum, platinum. If oxygen takes part in the reaction, cesium hydroxide very quickly destroys silver, gold. If you limit the flow of oxygen, the process is relatively slow, but still does not stop. Rhodium and several alloys of this compound are resistant to cesium hydroxide.
Apply wisely
Not only cesium, but also compounds known on the basis of this metal are currently used very widely. Without them, it is impossible to imagine the design of radio engineering, they are indispensable in electronics. The compound and variations of cesium are actively used in chemistry, industry, the ophthalmological sphere, and medical. Cesium is not ignored in the development of technologies applicable in space, as well as nuclear energy.
Currently, it is common to use cesium in the construction of solar cells. The bromide, iodide of this metal is necessary to create infrared vision systems. The single crystals obtained industrially can be used as detector elements, which allow fixing ionizing radiation. Some cesium-based compounds are actively used as catalysts in industrial processes. This is necessary when creating ammonia, forming ethylene oxide and producing butadiene.
Radiation and Cesium
The greatest attention of scientists is attracted by the cesium 137 isotope. It belongs to the category of beta emitters. Currently, this element is indispensable in the process of sterilization of food products, medicinal compounds. It is customary to resort to it in the treatment of malignant neoplasms. Modern approaches have allowed the use of the element in gamma-ray inspection. Based on it, level sensors as well as current sources are constructed. The 137th isotope was released into the environment in very large numbers after the accident at the Chernobyl nuclear power plant. It is he - one of the most important pollution factors after this disaster.
However, the 137th is not the only radioactive isotope of cesium that has found application in modern industry. So, atomic clocks are created on the isotope of cesium 133. At present, it is the most accurate device that allows you to control the passage of time. , , 9192631770 . 133 , .