Periodic Table -> Caesium


Caesium Details

Caesium Symbol: Cs

Caesium Atomic Number: 55

Caesium Atomic Weight: 132.90545

What is Caesium?

Caesium (atomic number 55, symbols Cs) is a an alkali metal with a silvery-gold color and the only liquid metal from the group of elemental metals, which is liquid near or at room temperature. The only other metals in a liquid form at/ around room temperature are mercury and gallium. Caesium has chemical and physical properties that resemble those of potassium and rubidium. It is pyrophoric and very reactive, and reacts with water at temperature of 177 F (116 C). Caesium is the least electronegative of elements with stable isotopes. It is extracted mainly from the zeolite mineral pollucite, while caesium-133 and other radioisotopes are extracted from waste materials generated by nuclear reactors.

In the US, the element is called cesium. The spectrum of the metal contains bright lines in the blue. Caesium is soft, silvery gold, and ductile, being the most alkaline and most electropositive element. In cold water, it reacts explosively, also reacting with ice when the temperature is above -116°C. Caesium hydroxide attacks glass and is a strong base.

In a study of patterns and rates of deposition and erosion on agricultural land, several conceptual benefits of the use of caesium were identified. First, it allows a retrospective evaluation of mid-term erosion rates. Second, the patterns and rates estimated are the total of all processes of erosion. Third, soil redistribution patterns and rates can be quantitatively assessed. Finally, extreme rates of soil redistribution have less influence on the estimated soil redistribution rates.

Caesium has found a number of practical applications, including in petroleum exploration, electronics and electric power, atomic clocks, isotope and nuclear applications, centrifugation fluids, and more. Caesium formate is used as a drilling fluid, which brings rock cuttings up to the ground, lubricates drill bits, and maintains pressure during the process of drilling.
Atomic clocks are made using caesium-133 atoms, observing electromagnetic transitions in them and using this as a reference point. It was only in 1955 when Louis Essen created the first accurate atomic clock at the British Physical Laboratory. Their accuracy was repeatedly improved since then, forming the basis for frequency and time measurements.

The element is used in low-power devices called caesium vapor thermionic generators, in which heat energy is converted into electrical energy. The current flow is enhanced by neutralizing space charge in the vacuum tube, which builds up around the cathode. The element has photoemissive properties which make it possible to convert light energy to electron flows. Caesium-based cathodes are used in photoelectric cells because of their low voltage for electrons’ emission. Among the photoemissive devices that use this element are video camera tubes, photomultiplier tubes, and optical character recognition. Other elements that can substitute it are silicon, selenium, rubidium, germanium, tellurium, and others. They can be used in photosensitive materials as well. Solutions of caesium sulfate, chloride, and trifluoroacetate are used due to their low density, particularly in molecular biology. They are commonly employed in density gradient ultracentrifugation. This method is mostly used to isolate fractions, sub-cellular organelles, nuclear acids, and viral particles from biological samples. Finally, caesium has limited application in chemistry, with caesium compounds improving the effectiveness of catalysts when different chemicals are produced. These include methanol, anthraquinone, phthalic anhydride, acrylic acid, ethylene oxide, various olefins, and others. Sulfur dioxide is converted to sulfur trioxide to produce sulfuric acid.

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