Xenon Configuration

[Piedad Coughlin]

Xenon is treated as noble gas but when you see its electronic configuration ,you will come to know that it's outermost shell have four electrons instead of eight electrons. This same happens with krypton also. I want to know why?

Xenon is element 54, in the noble gases (last) column. To get the short-handed electron configuration, look at the noble gas in the row above xenon. This would be krypton. This is the base that we use to form the configuration. So far, we have [Kr].

Starting from left to right, we fill in 2 electrons for the s orbitals. Since we haven't gotten to xenon yet, we need to fill in the d orbitals. This will be 10 electrons. Did we get there yet? Almost. We need to fill in the p orbitals to complete the configuration. We will fill all 6 electrons in. Now we got the electron configuration for xenon.

General DescriptionThe Good Xenon configurations use two Event Analyzers simultaneously to provide detailed spectral and temporal information about every event that survives background rejection. There are two pairs of Good Xenon configurations:

Good_Xenon1_2s with Good_Xenon2_2s (the 1 and 2 denote the two EAs; the 2s is the readout time)
Good_Xenon1_16s with Good_Xenon2_16s (again, the 1 and 2 denote the two EAs; 16s is the readout time).

Before you reduce Good Xenon data, you must combine matched pairs of files from the two EAs. The Perl script make_se will accomplish this task. The description of the data files that follows assumes the combination has been completed.Files containing Good Xenon data are in science event format. The science data occupy the XTE_SE extension in the form of individual time-stamped binary event words, one per line, which fill the Event column. The words themselves are strings of ones and zeros, the combinations of which define the properties of each event with respect to a template of all possible properties within the configuration. This template is broken up into sections - one for the PCU ID, one for the anode ID, and one for the PHA channel. Thus, an individual event word, with its particular combination of ones and zeros, picks out one PCU ID, one anode ID and one PHA channel. The time stamps occupy the Time column.Detailed DescriptionThe key to understanding and manipulating your Good Xenon data lies in "decoding" the event word template. The template itself occupies the TEVTB2 keyword in the header of the XTE_SE extension and is written in DDL - the Data Descriptor Language. Its value for Good Xenon is:(M[1]1,S[Zero]6,D[0:4]3,E[0:63]6,C[0:255]8)which, broken down into its parts, means:

• (M[1]1... ) - Unlike other event mode configurations, each row in a Good Xenon file contains only one kind of event, namely, valid science events. Like other other event mode configurations, these science events are identified with an M-token, the value of which is M[1]1.
• S[Zero]6 -Housekeeping check. Each valid bitmask is preceded by six zeroes.
• D[0:4]3 - Detectors 0-4, i.e. PCUs 0-4 (DDL's : symbol indicates a range). The 3 means that three bits are used to identify the PCU: 000 identifies PCU0, 001 PCU1, and so on.
• E[0:63]6 - Detector element, i.e. xenon anode. The 6 means that six bits are used to identify the Xe anode: 000001 identifies X1L, 000010 X1R, and so on. Note that some software, notably sefilter, requires the binary substring to be entered as a base-ten number, e.g. 1 identifies X1L, 2 X1R, 4 X2L, 8 X2R, and so on.
• C[0:255]8 - PCU Channel. Good Xenon provides the full 256 channel range. The 8 means that eight bits are used to identify one of the 2**8 channels.

Note that the readout time of the configuration (2 or 16 seconds) has no influence on the structure or properties of Good Xenon data. Its role is to provide observers with two telemetry choices. Note too that running fdump on a Good Xenon file will not provide an ASCII dump of the bitmask.Time and energy resolutionThe resolution of the time stamps in Good Xenon is 1/2**20 seconds, i.e. 0.95367431640625 microsec. This is the value of the TIMEDEL keyword in the header of the XTE_SE extension. Good Xenon provides the full 256-channel pass band of the PCA.Reduction requirements and optionsOnce make_se has been run on the Good_Xenon_1 and Good_Xenon_2pairs,the resulting files are reduced as event files usingseextrct. Apart from adjusting screening criteria, yourprimary reduction options include:

• Selecting (by applying a bitmask):
  • PCU IDs
  • anodes, i.e. layers
  • channels
• Binning the events into a light curve
• Binning the events into 256-channel spectra

For complete details on working with Event mode data and GoodXenondata, see the RXTE Cookbook recipe Reduction and Analysis of PCA Event-Mode Spectra. A further option is to convert the data from their event-word format into the more understandable, but more expansive, event file format which has explicit columns for the PCU ID etc. - similar to ASCA and ROSAT event lists. The conversion is effected, when you merge the two EAs, by running xenon2fits with the wrtparm=a option. Note that you will have to use the extractor ftool rather than seextrct to extract events. You will, however, be able to read the entire events file into xronos which cannot handle bitmasks at the moment.Gain and offsetGain and offset corrections are not applied by the EDS to Good Xenon data.Return, if you like, to the PCA Issues chapter or to the Table of Contents.The ABC of XTE is written and maintained by the RXTE GOF. Please email xte...@athena.gsfc.nasa.gov if you have any questions or comments. This particular page was last modified on Wednesday, 24-Aug-2022 11:10:28 EDT. A service of the Astrophysics Science Division at NASA/GSFC.

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For all their nobility, elements of group 18 have lived in relative obscurity. In 1869, Mendeleev's first periodic table did not include them, as closed-shell elements remained undiscovered until Lord Rayleigh and William Ramsey isolated argon in 1894. Remarkably, Ramsey then went on to isolate helium (1895) and radon (1908) and, with Morris Travers, to discover krypton, neon and xenon (1898). It was debated whether the 'inert' monoatomic gases belonged to the periodic table owing to their lack of 'chemical properties'; elements coming late to the party, with no unpaired electrons to share, may not get a seat at the table. But Ramsey established their position between halogens and alkali metals, and was awarded the Nobel Prize in Chemistry in 1904 for these elemental contributions.

Xenon now finds uses in fields as varied as lasers and incandescent lamps, plasma display panels, silicon etching in semiconductor manufacturing and medicine. In 2008, twelve million litres of xenon were extracted from the atmosphere, and production is growing to meet technological needs.

Xenon's polarizability (about 4 compared with 0.2 for He) contributes to its affinity for hydrophobic cavities in proteins, which is relevant not only for protein crystallography but also for anaesthetic use. Behnke deduced that xenon was an anaesthetic in 1939, after observing 'drunkenness' in deep-sea divers, and it was first used for surgical purposes in 1951. It has gained newfound popularity, based on its non-toxicity and low environmental impact (compared with halocarbons), and a xenon-based anaesthetic (LENOXe) was commercialized in 2007.

Xenon has more than 50 isotopes, including nine stable ones (second only to tin, which has ten). 129Xe, with a spin-1/2 nucleus, provides large NMR signals for imaging studies in the lungs. Moreover, the 129Xe NMR chemical shift is extremely sensitive to stereo-electronic perturbations of the 129Xe atom, and xenon biosensors based on these phenomena are now under development.

The inertness of noble gases makes them useful whenever chemical reactions are unwanted. For example, argon is used as a shielding gas in welding and as a filler gas in incandescent light bulbs. After the risks caused by the flammability of hydrogen became apparent in the Hindenburg disaster, hydrogen was replaced with helium in blimps and balloons. Helium and neon are also used as refrigerants due to their low boiling points. Industrial quantities of the noble gases, except for radon, are obtained by separating them from air using the methods of liquefaction of gases and fractional distillation. Helium is also a byproduct of the mining of natural gas. Radon is usually isolated from the radioactive decay of dissolved radium, thorium, or uranium compounds.

The seventh member of group 18 is oganesson (Og), an unstable synthetic element whose chemistry is still uncertain because only five very short-lived atoms (t1/2 = 0.69 ms) have ever been synthesized (as of 2020[update][3]). IUPAC uses the term "noble gas" interchangeably with "group 18" and thus includes oganesson;[4] however, due to relativistic effects, oganesson is predicted to be a solid under standard conditions and reactive enough not to qualify functionally as "noble".[3] In the rest of this article, the term "noble gas" should be understood not to include oganesson unless it is specifically mentioned.

Noble gas is translated from the German noun Edelgas, first used in 1900 by Hugo Erdmann[5] to indicate their extremely low level of reactivity. The name makes an analogy to the term "noble metals", which also have low reactivity. The noble gases have also been referred to as inert gases, but this label is deprecated as many noble gas compounds are now known.[6] Rare gases is another term that was used,[7] but this is also inaccurate because argon forms a fairly considerable part (0.94% by volume, 1.3% by mass) of the Earth's atmosphere due to decay of radioactive potassium-40.[8]

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