Elemental Profile
Cesium
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The chemical symbol of the element cesium is Cs, and its atomic number is 55, which is an element of the s-region of the sixth cycle, group IA.
Cesium salts exist in minerals in nature, and a small amount of cesium chloride also exists in carnallite. It is produced by reducing cesium chloride with calcium.
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Process of discovery
In 1860, Bunsen and Kirchhoff, in Germany, discovered cesium during spectroscopic experiments on extracts from mineral springs.
Spectral analysis is more sensitive than chemical analysis, and cesium, rubidium, thallium, and indium, which are found in small amounts in the earth's crust, were arrested by the barrier of spectroscopic analysis after escaping analytical chemists.
In 1860, the year Bunsen and Kirchhoff created spectral analysis, they used a spectroscope to discover the presence of a new alkali metal in concentrated Durkheim mineral water. In a report they recounted, "After evaporating 40 tons of mineral water, precipitating the lime, strontium and bitter clays, and removing the lithium clays with ammonium carbonate, the filtrate obtained showed in the spectroscope, in addition to the spectral lines of sodium, potassium, and lithium, two bright blue lines in the vicinity of the strontium line. There is no known simple substance that shows these two blue lines in this part of the spectrum. After examination it can be concluded that an unknown simple substance must exist, belonging to the alkali metal group. We propose to call this substance Cesium (Cesium), with the symbol Cs. The name comes from the Latin caesius, which was used in ancient times to refer to the blue color of a clear sky. ......"
In fact, as early as 1846, Plattler, a professor of metallurgy at Freiberg, Germany, was analyzing ores of lepidote (also known as red mica) when he mistook cesium sulfate for a mixture of sodium and potassium sulfate. The cesium slipped through his hands.
Cesium metal was not obtained until 1882, when the German chemist Setterberg electrolyzed a mixture of cesium cyanide and barium cyanide.
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General properties
Period: VI
Group: IA
Partition: s
Concentration in the Sun: 0.008 ppm
Concentration in seawater: 30,000 ppm
Concentration in the Earth's crust: 3 ppm
Atomic weight: 132.9
Atomic radius: 260 pm
***Valence radius: 225 pm
Oxidation state: +1 (predominantly)-1
Electronegativity: 0.79 (Bowling scale)
Most stable isotope: 133Cs
Crystalline cell parameters:
a = 614.1 pm
b = 614.1 pm
c = 614.1 pm
α = 90°
β = 90°
γ = 90°
Ionization energy (kJ /mol)
M - M+ 375.7
M+ - M2+ 2420
M2+ - M3+ 3400
M3+ - M4+ 4400
M4+ - M5+ 6000
M5+ - M6+ 7100
M6+ - M7+ 8300
M7+ - M8+ 11300
M8+ - M9+ 12700
M9+ - M10+ 23700
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Physical Properties
Color: silver-white (with a slight golden luster) Density: 1.879g/cm^3 Mohs Hardness: 0.2 Melting Point: 28.40°C Boiling Point: 678.4°C Specific Heat Capacity: 240 J/(kg-K) Electrical Conductivity: 4.89×106/(m-Ω) Thermal Conductivity: 35.9 W /(m-K) Heat of vaporization: 67.74 kJ/mol Heat of melting: 2.092 kJ/mol Vapor pressure: 2500 Pa (1112K)
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Chemical properties
Molar volume: 71.07 cm^3/mol
Crystalline structure: body-centered cubic lattice
Cesium is found in air. Generates a gray-blue layer of cesium oxide, which burns up in less than a minute, emitting a rose-colored flame and generating cesium peroxide and cesium superoxide.
Cesium is the most active of the alkali metals and can react violently with oxygen to produce a variety of cesium oxides. In humid air, the heat of oxidation is sufficient to melt and burn cesium. Cesium does not react with nitrogen, but can react with hydrogen at high temperatures to produce fairly stable hydrides. Cesium can react violently with water. If you put cesium into a sink filled with water, it will explode immediately, so be careful when doing the reaction. Even ice with a temperature as low as -116°C can react violently to produce hydrogen and cesium hydroxide, and the resulting cesium hydroxide is the most alkaline of the hydroxide bases. Stable halides can also be produced with halogens, a characteristic due to its large ionic radius. Cesium reacts with organic substances similarly to other alkali metals, but it is more reactive. Cesium chloride is its main compound.
Cesium salts are soluble in all salt solutions, as are potassium and sodium salts. (Perchlorate is insoluble.)
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Elemental Uses
In the presence of light, cesium emits electrons, and cesium metal is mainly used in the manufacture of phototubes, photocells, registrars, scintillation counters, radio tubes, military infrared signal lamps, and in a wide variety of optical and detection instruments. Its compounds are used in the production of glass and ceramics, as an absorbent in carbon dioxide purification devices, radio electronic tube suction agent and trace chemistry. In medicine cesium salts are also used as anti-shock agents after taking arsenic-containing drugs. The isotope cesium-137 can be used to treat cancer.
The atomic clocks it makes are extremely accurate, with an error of one second per three million years. In the International System of Units (SI), one second is now formulated as the time it takes for 9,192,631,770 weeks of radiation to jump between two hyperfine energy levels in the ground state of a cesium-133 atom in a zero magnetic field.
The most accurate timekeeping instrument
The most accurate timekeeping instrument that can be made from cesium is the atomic clock. Cesium atomic clocksAs soon as we talk about clocks, you naturally understand that this is a tool for measuring time. Human life and production activities can not be separated from the timekeeping, think about it, if one day after getting up, all the clocks in the world have disappeared, what will the world become like?
In the past, people determined the time to take the rotation of the Earth as a benchmark. The Earth is a natural timepiece, and it rotates on its axis once every day and night, year after year. The time it takes for the Earth to rotate on its axis is one day -- twenty-four hours -- and one eighty-six thousand four-hundredth of that is one second, which is how the unit of time, the second, came to be.
But it was later discovered that the Earth is not a very accurate "clock" due to tidal forces and many other factors. It rotates at an erratic rate, sometimes fast and sometimes slow. Although the difference in speed is very small, it adds up to a very large error.
Is there a more accurate timekeeping device?
People began to break the old traditional habits, the big end does not work, to the small end of the exploration. People found: the sixth layer of the cesium atom -- that is, the outermost layer of electrons rotating around the nucleus of the atom, always extremely accurate in billions of fractions of a second to complete a circle, stability than the Earth's rotation around the axis of much higher. Using this feature of the cesium atom, people made a new type of clock - the cesium atomic clock, stipulating that one second is the time it takes for the cesium atom to "vibrate" 9192631770 times (i.e., the equivalent of the cesium atom's outermost electrons to rotate so many times). This is the latest definition of "second".
Using cesium atomic clocks, people can very accurately measure the time to one billionth of a second, with a precision and stability that far exceeds that of any watch the world has ever seen before, and exceeds that of astronomical time, which has been benchmarked against the Earth's rotation for many years.
The creative labor of mankind has been rewarded. As we all know, in our daily lives, it is enough to know the year, the month, the day as well as the hour, the minute and the second. But modern science and technology often need to accurately measure much shorter periods of time, such as milliseconds (thousandths of a second), microseconds (millionths of a second), and so on. With clocks such as the cesium atomic clock, human beings can engage in more detailed scientific research and production practices, such as the explosion of atomic and hydrogen bombs, the launch of rockets and missiles, as well as cosmic navigation, etc., the implementation of highly accurate control, of course, can also be used for long-distance flight and navigation.
Traveling in space
In order to conquer the universe, a new and extremely fast vehicle is necessary. General rockets, spaceships can not reach this speed, at most, can only be out of the Earth-Moon system; only can fly more than 100,000 kilometers per hour "ion rocket" to meet the requirements.
As we said earlier, the outermost electrons of cesium atoms are extremely unstable, and can easily be excited and radiated into positively charged cesium ions, making it an ideal "fuel" for ion rocket engines for cosmic navigation.
The working principle of the cesium ion rocket is like this: after the engine is started, a large amount of cesium vapor is produced, and the cesium vapor becomes positively charged cesium ions through the "processing" of the ionizer, and then accelerates to 150 kilometers per second under the action of the magnetic field, and ejects it from the nozzle, and at the same time, it gives the ion rocket a strong impetus, and pushes the rocket highly forward. that pushed the rocket highly forward.
Calculations show that using such cesium ions as a propellant for cosmic rockets produces hundreds of times more thrust per unit weight than the liquid or solid fuels used today. Such cesium ion rockets could travel in cosmic space for a decade or more!
Japan
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Hazards of cesium in nuclear leaks
Tiny amounts of the artificial radionuclides cesium-137 and cesium-134 were also detected in aerosol samples taken from monitoring sites in Anhui Province, Guangdong Province, the Guangxi Zhuang Autonomous Region, and the Ningxia Hui Autonomous Region on March 29, and the concentrations of these were in the 10-5 Bq/m3 order of magnitude and below The concentrations were all in the order of 10-5 Bq/m3 and below. Cesium-137 in the environment is easily absorbed into the human body and evenly distributed throughout the body; since cesium-137 can emit γ-rays, it is easily measured outside the body. Radioactive cesium entering the body mainly stays in the soft tissues of the whole body, especially in the muscles, with a lower concentration in bone and fat; a larger amount of radioactive cesium ingested into the body can cause acute and chronic injuries.
Cesium-137 can be used as a source of gamma radiation for radiation breeding, irradiation storage of food, sterilization of medical equipment, treatment of cancer, and gamma probing of industrial equipment. Because of the long half-life of the cesium source and its vulnerability to proliferation, the cesium-137 source has been gradually replaced by the cobalt-60 source in recent years
Radioactive cesium and its brief properties
Nuclide Chemistry
Symbol Atomic
Ordinance Primary radioactivity
Isotope Half-life Source Toxicity
Cesium Cs 55 137Cs 30.0 years Artificial poisoning