9/21/2023 0 Comments Melting point of caesium![]() ![]() ![]() ![]() The grey spheres represent the caesium atoms. 8 spheres form a regular cube and 8 of those cubes form a larger cube. Caesium is the most electropositive stable chemical element.Ģ7 small grey spheres in 3 evenly spaced layers of nine. Some small differences arise from the fact that it has a higher atomic mass and is more electropositive than other (non-radioactive) alkali metals. The chemistry of caesium is very similar to that of other alkali metals, and is particularly closely associated to that of rubidium, the element above caesium in the periodic table. When glass ampoules are used, they are shipped wrapped in foil and packed in an inert cushioning material, such as vermiculite, each in a metal can. ![]() In quantities of more than about 100 grams, caesium is shipped in hermetically sealed stainless steel containers. It is stored and shipped in dry mineral oil or in other dry saturated hydrocarbons or in an inert atmosphere or vacuum in sealed borosilicate glass ampoules. Because of its high reactivity, the metal is classified as a hazardous material. The reaction with solid water occurs even at temperatures as low as −116 ☌. In addition to igniting spontaneously in air, it reacts explosively with water (even cold), even more so than the other members of the first group of the periodic table. Isolated caesium is extremely reactive and very pyrophoric. High purity caesium-133 preserved under argon Y shaped yellowish crystal in glass ampoule, looking like the branch of a pine tree A couple of amalgams have been studied, including the black-metallic, purple shining CsHg2 and the golden-metallic CsHg. The alloy of 41 at.% caesium, 47 at.% potassium, and 12 at.% sodium has the lowest melting point of any known metal alloy, at −78 ☌. On the other hand, it is known to form intermetallic compounds with antimony, gallium, indium and thorium, which are known to be photosensitive. At temperatures below 650 ☌, it alloys with cobalt, iron, molybdenum, nickel, platinum, tantalum or tungsten. Caesium compounds burn with a blue color.Ĭaesium forms alloys with the other alkali metals as well as with gold, and amalgams with mercury. Mercury is the only metal with a known melting point lower than caesium. It has a melting point of 28.4 ☌, making it one of the few metals that are liquid near room temperature. While the element has a mild chemical toxicity, the radioisotopes present a high health risk in case of radiation leaks and has been named a hazardous material.Ĭaesium is a very soft, very ductile, silvery-white metal, which develops a silvery-gold hue in the presence of trace amounts of oxygen. The radioactive isotope caesium-137, with a half-life of about 30 years, is used in medical applications, industrial gauges, and hydrology. It has a range of applications in the production of electricity, in electronics, and in chemistry. Since the 1990s, the largest application of the element has been as caesium formate for drilling fluids. Since then it has been widely used in atomic clocks. In 1967, a frequency of caesium-133 was used to define the second by the International System of Units. The first small-scale applications for caesium have been as "getter" in vacuum tubes and in photoelectric cells. The two German chemists Robert Bunsen and Gustav Kirchhoff discovered it in 1860 by the newly developed method of flame spectroscopy. This is mined mostly from pollucite, while the radioisotopes, especially caesium-137, are extracted from waste produced by nuclear reactors. It is the least electronegative element that has stable isotopes, of which it has only one, caesium-133. The metal is extremely reactive and pyrophoric, reacting with water even at −116 ☌. Caesium has physical and chemical properties similar to those of rubidium and potassium. It is a soft, silvery-gold alkali metal with a melting point of 28 ☌ (83 ☏), which makes it one of only five metals that are liquid at or near room temperature. Caesium or cesium is the chemical element with the symbol Cs and atomic number 55. ![]()
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