Xenon elements

For krypton and xenon abundances were derived from computer hts of aN (neutron capture cross-section times abundance) versus mass number. Nuclei that are shielded from the r-process, so-called s-only nuclei, were used for the ht and the abundances of Kr and Xe were calculated. From these data, and the isotopic composition of the solar wind, the krypton and xenon elemental abundances were calculated (Palme and Beer, 1993) and are listed in Table 1. The meteorite data given in Table 1 will be discussed in a later section. 

There are a number of novel xenon-element bonds which have been characterized in species that have not been obtained in bulk quantities but have been identified by mass spectrometry or by matrix-isolation spec-... 

Chemical properties and spectroscopic data support the view that in the elements rubidium to xenon, atomic numbers 37-54, the 5s, 4d 5p levels fill up. This is best seen by reference to the modern periodic table p. (i). Note that at the end of the fifth period the n = 4 quantum level contains 18 electrons but still has a vacant set of 4/ orbitals. 

Survey and account for the group characteristics and trends in the elements of Group O (He-Rn). Outline the preparation and stereochemistry of xenon tetrafluoride. 

Gr. xenon, stranger) Discovered by Ramsay and Travers in 1898 in the residue left after evaporating liquid air components. Xenon is a member of the so-called noble or "inert" gases. It is present in the atmosphere to the extent of about one part in twenty million. Xenon is present in the Martian atmosphere to the extent of 0.08 ppm. the element is found in the gases evolved from certain mineral springs, and is commercially obtained by extraction from liquid air. 

Noble gases (Section 1 1) The elements in group VIIIA of the penodic table (helium neon argon krypton xenon radon)... 

The upper part of the figure illustrates why the small difference in mass between an ion and its neutral molecule is ignored for the purposes of mass spectrometry. In mass measurement, has been assigned arbitrarily to have a mass of 12.00000, All other atomic masses are referred to this standard. In the lower part of the figure, there is a small selection of elements with their naturally occurring isotopes and their natural abundances. At one extreme, xenon has nine naturally occurring isotopes, whereas, at the other, some elements such as fluorine have only one. 

For organometailic compounds, the situation becomes even more complicated because the presence of elements such as platinum, iron, and copper introduces more complex isotopic patterns. In a very general sense, for inorganic chemistry, as atomic number increases, the number of isotopes occurring naturally for any one element can increase considerably. An element of small atomic number, lithium, has only two natural isotopes, but tin has ten, xenon has nine, and mercury has seven isotopes. This general phenomenon should be approached with caution because, for example, yttrium of atomic mass 89 is monoisotopic, and iridium has just two natural isotopes at masses 191 and 193. Nevertheless, the occurrence and variation in patterns of multi-isotopic elements often make their mass spectrometric identification easy, as depicted for the cases of dimethylmercury and dimethylplatinum in Figure 47.4. 

Del y for Dec y. Nuclear power plants generate radioactive xenon and krypton as products of the fission reactions. Although these products ate trapped inside the fuel elements, portions can leak out into the coolant (through fuel cladding defects) and can be released to the atmosphere with other gases through an air ejector at the main condenser. 

K [14881-07-3], Rb [72151 -96-3], and Cs [72138-72-8]), are prepared by reaction of elemental fluorine, chlorine trifluoride, or xenon difluoride and a mixture of nickel fluoride and alkaH metal fluorides or other metal haHdes (16,17). If the fluorination is carried out using mixed fluorides, a lower temperature can be used, yields are quantitative, and the final products are of high purity. Bis(tetrafluoroammonium) hexafluoronickelate [6310540-8], (NE 2N iF6> prepared from Cs2NiF3 and NE SbE by a metathesis in anhydrous HE, is also known (18). 

Derivatives. The nonmetaHic inorganic derivatives of fluorosulfuric acid are generally made indirectly, although complex fluorosulfates of the Group 15 (V) elements and of xenon can be made directly (85,86), as can the NO" and NO" 2 salts (26,27). 

Argon-40 [7440-37-1] is created by the decay of potassium-40. The various isotopes of radon, all having short half-Hves, are formed by the radioactive decay of radium, actinium, and thorium. Krypton and xenon are products of uranium and plutonium fission, and appreciable quantities of both are evolved during the reprocessing of spent fuel elements from nuclear reactors (qv) (see Radioactive tracers). 

Pure Elements. AH of the hehum-group elements are colorless, odorless, and tasteless gases at ambient temperature and atmospheric pressure. Chemically, they are nearly inert. A few stable chemical compounds are formed by radon, xenon, and krypton, but none has been reported for neon and belium (see Helium GROUP, compounds). The hehum-group elements are monoatomic and are considered to have perfect spherical symmetry. Because of the theoretical interest generated by this atomic simplicity, the physical properties of ah. the hehum-group elements except radon have been weU studied. 

Except for helium, all of the elements in Group 18 free2e into a face-centered cubic (fee) crystal stmeture at normal pressure. Both helium isotopes assume this stmeture only at high pressures. The formation of a high pressure phase of soHd xenon having electrical conductivity comparable to a metal has been reported at 33 GPa (330 kbar) and 32 K, and similar transformations by a band-overlap process have been predicted at 15 GPa (150 kbar) for radon and at 60 GPa (600 kbar) for krypton (51). 

Different combinations of stable xenon isotopes have been sealed into each of the fuel elements in fission reactors as tags so that should one of the elements later develop a leak, it could be identified by analyzing the xenon isotope pattern in the reactor s cover gas (4). Historically, the sensitive helium mass spectrometer devices for leak detection were developed as a cmcial part of building the gas-diffusion plant for uranium isotope separation at Oak Ridge, Tennessee (129), and heHum leak detection equipment is stiU an essential tool ia auclear technology (see Diffusion separation methods). 

Xenon difluoride has been used to oxidize a number of antimony compounds [102, 109] in yields ranging from 73 to 98%. Elemental fluorine oxidized tris(pen-tafluorophenyl)stibine to tris(pentafluorophenyl)stibine difluoride in 98% yield [706]. Oxidative fluonnation of stibines has also been accomplished with iodine pentafluoride [707]. 

Xenon difluoride is used to prepare methyliodine difluoride from methyl iodide [102, 128] as well as to convert miscellaneous aryl [103, 129, 110] heptafluorapropyl [129], and 2,2,2-trifluoroethyl [103] iodides to the corresponding organo iodine difluorides in yields ranging from 60 to 100% Elemental fluorine transforms aryl iodides to their corresponding aryliodine difluoride turn pounds [131 132], which are known to add fluorine to alkenes ]133] (equation 21)... 

The stability of the electronic configuration is indicated by the fact that each element has the highest ionization energy in its period, though the value decreases down the group as a result of increasing size of the atoms. For the heavier elements is it actually smaller than for first-row elements such as O and F with consequences for the chemical reactivities of the noble gases which will be considered in the next section. Nuclear properties, particularly for xenon, have been exploited for nmr spectroscopy and Mdssbauer... 

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