![]() Krypton has many ofthe chemical properties and characteristics of some of the other noble gases. Krypton is the fourth element in group 18 (VIIIA), which is also known as group 0 becausethe elements is this group were thought to have a zero oxidation point. Krypton gas presently costs about $690/100 L. Uses thus far have been limited because of its high cost. Krypton is used in certain photographic flash lamps for highspeed photography. Estimates of the concentration of reactants are therefore made possible. The activity of these kryptonates is sensitive to chemical reactions at the surface. By imbedding the isotope in various solids, kryptonates are formed. 85Kr has found recent application in chemical analysis. Krypton clathrates have been prepared with hydroquinone and phenol. Molecule-ions of ArKr+ and KrH+ have been identified and investigated, and evidence is provided for the formation of KrXe or KrXe+. A higher fluoride of krypton and a salt of an oxyacid of krypton also have been prepared. Krypton difluoride has been prepared in gram quantities and can be made by several methods. While krypton is generally thought of as a noble gas that normally does not combine with other elements, the existence of some krypton compounds has been established. Solid krypton is a white crystalline substance with a face-centered cubic structure that is common to all the rare gases. In October 1983 the meter was again redefined by the International Bureau of Weights and Measures as being the length of path traveled by light in a vacuum during a time interval of 1/299,792,458 of a second. This replaced the standard meter of Paris, which was defined in terms of a bar made of a platinum-iridium alloy. In 1960 it was internationally agreed that the fundamental unit of length, the meter, should be defined in terms of the orange-red spectral line of 86Kr. The spectral lines of krypton are easily produced and some are very sharp. Thirty other unstable isotopes and isomers are now recognized. Naturally occurring krypton contains six stable isotopes. ![]() It is characterized by its brilliant green and orange spectral lines. The atmosphere of Mars has been found to contain 0.3 ppm of krypton. Historyĭiscovered in 1898 by Ramsay and Travers in the residue left after liquid air had nearly boiled away, krypton is present in the air to the extent of about 1 ppm. There are traces of krypton in some minerals and meteorites. Along with some other gases, it is removed by filtering through activated charcoaland titanium. Krypton shows up as an impurity inthe residue. The gas is capturedcommercially by fractional distillation of liquid air. Krypton is expensive to produce and thus has limited use. It ranks just above methane (CH 4) in abundancein the atmosphere. Krypton is the 81st most abundant element on Earth and ranks seventh in abundance ofthe gases that make up Earth’s atmosphere. The name “krypton” is derived from the Greek word kryptos, meaning All the others are radioactive, man-made by-productsof nuclear power plants and radioactive isotopes with half-lives ranging from 107 nanosecondsto 2.29×10 +15 years. The isotope Kr-78 has such a long half-life (0.9×10 +20years) that it is considered stable even though it contributes only 0.35% to the naturalkrypton in the Earth’s atmosphere. There are a total of 37 isotopes of krypton. Krypton’s melting point is –156.6☌, its boiling point is –152.30☌, and its density is0.003733g/cm 3. However, in 1967 scientists were able tocombine fluorine with krypton at low temperatures to form the compound krypton difluoride(KrF 2). At one time it was thought that krypton, aswell as the other noble gases, were completely inert. It is extracted during fractional distillation ofliquid oxygen at a temperature of about –63.8☌. Its critical temperature isbetween that of oxygen and carbon dioxide. ![]() Krypton is a rather dense, tasteless, colorless, odorless gas. Its primary uses are in the activation of phosphors for self-luminous markers, detecting leaks, and in medicine to trace blood flow. Radioactive isotopes of krypton are shipped under radioactive labels and placards as required. These forms of krypton are not radioactive. ![]() The four-digit UN identification number for krypton is 1056 as a compressed gas and 1970 as a cryogenic liquid. Krypton 85 is radioactive and has a half-life of 10.3 years. It is noncombustible, nontoxic, and nonreactive however, it is an asphyxiant gas and will displace oxygen in the air. Krypton, Kr, is an elemental, colorless, odorless inert gas.
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