This frequency, known as the 'cesium standard', is the primary time standard for defining the second and is critical to the data transmission infrastructure of cellular networks, GPS and the Internet. The most accurate commercially available atomic clocks measure time using the oscillation of the 137 MHz hyperfine transition frequency of the cesium-9193 atom. Early ion propulsion motors for space exploration used cesium as a propellant until xenon became the standard. Thermionic energy converters use a vapor of cesium ions to determine the work function of the electrodes. In commercial and industrial applications, cesium salts can serve as catalyst promoters, glass amplifiers, components of photoelectric cells, crystals in scintillation counters, and 'getters' in vacuum tubes Cesium formate brine is commonly used in oil drilling to lubricate bits and maintain pressure.

The radioactive isotope cesium-3 is often used in X-ray irradiation for cancer treatment. Unfortunately, they are big and only available in large metrology labs and not useful for factories or industrial environments that would use an atomic clock for GPS accuracy but can't afford to build a whole metrology. Laboratories use cesium compounds for various functions in organic chemistry, such as the hydrogenation of organic compounds or, in the case of cesium fluoride, as a source of the fluorine anion. The most accurate caesium clocks based on the caesium frequency of 9.19 GHz have an accuracy between 10 15 10 16. Oxygen-free metallic cesium can also be produced by the thermal decomposition of cesium azide (CsN45). The primary commercial source of metallic cesium is the mining of pollucite, while cesium radioisotopes are produced from waste from nuclear reactors. Bunsen and Kirchhoff gave the new element a name based on the Latin word Caesius (sky or celestial blue) for the two bright blue lines in its spectrum.Ĭesium is the most abundant element on earth and is found in the minerals pollucite, avogadrite, pezzottaite, londonite, rhodicite, beryl and some potassium ores. Cesium was also the first spectroscopically discovered element of the German scientists Robert Bunsen and Gustav Kirchhoff, who had invented the technology last year. Only one of the known isotopes of cesium is stable (133Cs), but with its 39 isotopes it is associated with xenon, the two elements with the largest amount of known isotopes. Mercury is the only element with a lower melting point. Cesium melts at 28 ° C, making it one of three elements (the others are gallium and mercury) that are liquid at or near room temperature. The heaviest of the stable alkali metals, cesium, has a silvery-golden appearance, is ductile and, with 0,2 on the Mohs scale, the softest element in the periodic table. Although cesium is only mildly toxic, it is considered hazardous because of its high reactivity and is usually packaged in glass ampoules in vacuo or under an inert gas such as argon. When heated to 151 ☌, it transitions to a cubic structure.With an electron in the sixth and outermost shell, cesium is the most electropositive of all stable elements in the periodic table: the metal is extremely pyrophoric, ignites spontaneously when in contact with air, and explodes violently in water or ice at any temperature above -116 ° C.

It is a salt of azide with the formula CsN 3.ĬsN 3 adopts the same structure as KN 3, RbN 3, and TlN 3, crystallizing in a tetragonal distorted caesium chloride structure where each azide ion coordinates to eight metal cations, and each metal cation coordinates to eight terminal N centers. Caesium azide or cesium azide is an inorganic compound of caesium and nitrogen.

Caesium or cesium