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Element 112 longest-lived isotopes

The other actinides have been synthesized in the laboratory by nuclear reactions. Their stability decreases rapidly with increasing atomic number. The longest lived isotope of nobelium (102N0) has a half-life of about 3 minutes that is, in 3 minutes half of the sample decomposes. Nobelium and the preceding element, mendelevium (ioiMd), were identified in samples containing one to three atoms of No or Md. [Pg.147]

The element was generated by bombardment of californium with boron in a linear accelerator. The priority is debated. Isotopes of the elements were observed both by the group of Glenn T. Seaborg and by that of G. N. Flerov in Dubna. IUPAC proposed that the priority be shared. The longest-lived isotope has a half-life of 200 minutes. Lawrencium ends the series of actinides, as the 5f level is fully occupied with 14 electrons. [Pg.86]

The element exists as an intermediate in uranium and thorium minerals through their decay. There is no stable isotope. The longest-living isotope has a half-life of 8.3 hours. In the crust of the Earth, the total steady-state mass is estimated at a few tens of grams. Thus astatine is the rarest element (record ). A few atoms of this relative of iodine can be found in all uranium ore. It exhibits certain metallic properties. [Pg.153]

Like einsteinium, this unstable element was discovered in the fallout from the first hydrogen bomb. To date, only fragments in microgram amounts can be isolated. 258Fm ends the series of transuranium elements that can be produced in a reactor by neutron bombardment. The longest-lived isotope decays with a half-life of 100 days... [Pg.158]

Radioactive, short-lived element. The longest-lived isotope (256Md) has a half-life of 55 days. To date, only a few atoms have been prepared by a nuclear reaction between einsteinium and helium nuclei in a particle accelerator. [Pg.158]

Atomic weights are those of the most commonly available long-lived isotopes on the 1999 lUPAC Atomic Weights of the Elements A value given in square brackets denotes the mass number at the longest-lived isotope... [Pg.428]

Symbol Pu atomic number 94 atomic weight 244 an actinide series transuranium element a man-made radioactive element electron configuration [Rn]5/ 7s2 partially filled f suhsheU valence states +3, +4, -i-5, +6 eighteen isotopes in the mass range 228-230, 232-246 aU isotopes radioactive the longest lived isotope Pu-244, ti/2 8.2x10 year the shortest hved isotope Pu-233, ti/2 20.9 minute. [Pg.726]

In 1940 D. R. Corson, K. R. Mackenzie, and E. Segre at the University of California bombarded bismuth with alpha particles (26, 27). Preliminary tracer studies indicated that they had obtained element 85, which appeared to possess metallic properties. The pressure of war work prevented a continuation of these studies at the time. After the war, the investigators resumed their work, and in 1947 proposed the name astatine, symbol At, for their element. The name comes from the Greek word for unstable, since this element is the only halogen without stable isotopes (28). The longest lived isotope is At210 with a half-life of 8.3 hours and a very high activity. [Pg.865]

The failure to discover francium earlier is easy to understand when it is remembered that the half-life of the longest lived isotope is only 21 minutes. This gives the element the distinction of being the most unstable to radioactive disintegration of all elements up to number 98 (38). It is also noteworthy that this is the only element in the group discussed in this chapter which was not discovered by artificial preparation in the laboratory. Nevertheless, the rarity of actinium in nature is so great that this element is best prepared artificially when its properties or those of its daughter elements are to be studied. [Pg.867]

Element has no stable nuclides. The value enclosed in brackets, e.g. (209), indicates the mass number of the longest lived isotope of the element. However, three such elements (Th, Pa, and U) do have a characteristic terrestrial isotopic composition, and for these an atomic weight is tabulated. [Pg.472]

Up to 1970, it was thought that the practical limit of the periodic table would be reached at about element 108. By extrapolating the experimental data on heavy-element half-lives, we concluded that the half-lives of the longest-lived isotopes of the heavy elements beyond about element 108 would be so short (<10-6 s) due to spontaneous fission decay that we could not produce and study them (Fig. 15.10). However, in the late 1960s and early 1970s, nuclear theorists, using techniques developed by Vilen Stmtinsky and Wladyslaw Swiatecki, predicted... [Pg.447]

Figure 15.10 Half-lives of the longest-lived isotope of each element versus atomic number Z circa 1970. (Figure also appears in color figure section.)... Figure 15.10 Half-lives of the longest-lived isotope of each element versus atomic number Z circa 1970. (Figure also appears in color figure section.)...
The vertical profile of francium (Fr), markedly different from other Group 1 elements, is based on calculation rather than direct measurement. 223Fr, the longest-lived isotope of francium and a daughter of 227Ac, is formed with a branching ratio of approximately 1.4%. With a half-life of 22 min (compared to the 22-year half-life of 221 Ac) it should exist in seawater, in minute quantities, in direct proportion to the concentration of 227Ac. [Pg.330]

The listed mass is that for the longest-lived isotope of the listed element. [Pg.392]

Each element in the table is listed with (from top to bottom) its atomic number, its name, its symbol, and its atomic mass. Atomic mass numbers in parentheses are the mass numbers of the longest-lived isotope. Other atomic mass numbers are the average mass number... [Pg.315]

Li, Rb and Cs are of lower abundance and are obtained from silicate minerals. Francium (Fr) is a radioactive element and occurs in very small quantities in uranium minerals. The longest-lived isotope of francium is 223Fr (ty2 = 22 min). [Pg.63]

Table Longest-lived isotopes of actinides Atomic no. Element Isotope Half-life... [Pg.281]

Technetium was the first of the artificially produced elements (1937) when it was obtained, as the isotopes 95Tc and Tc, by bombarding Mo with deuterons. Today twenty-one isotopes, all radioactive, are known with mass numbers 90-111. The longest lived isotope is Tc (ha 4 x 106 y), but the commonest is "Tc (tm — 2 x 105 y). It is isolated in fairly large quantities from spent nuclear fuel, where it constitutes ca. 6% of the fission products. The total amount of "Tc is about 78 tons, which exceeds the known amount of rhenium in the earth s crust. "Tc emits a soft (293.6 Kev) /3 particle and can be handled with only very modest precautions. [Pg.977]

Table 9.1 Longest-lived isotopes of the actinide elements... Table 9.1 Longest-lived isotopes of the actinide elements...
Study of the chemical properties of element 104 has confirmed that it is indeed homologous to hafnium as demanded by its position in the Periodic Table (20). Chemical studies have been made for element 105, showing some similarity to tantalum (25) no chemical studies have been made for elements 106—109. Such studies are very difficult because the longest-lived isotope of 104 (261104) has a half-life of only about 1 min, of 105 (262105) a half-life of about 40 s, of 106 (2<53106) a half-life of about 1 s, and of elements 107—109 half-lives in the range of milliseconds. [Pg.225]

On account of this element s rarity, a separate account of it is desirable. Although the existence of promethium was predicted as early as 1913, it was not definitely discovered until 1945, since all isotopes are radioactive with the longest-lived isotope having a half-life of 17.7 years ( " Pm). It is a fission product of and is thus obtained on work-up of reprocessing wastes. [Pg.4235]

Such methods have allowed all the elements of the 6d series, i.e. to Z = 112, to be produced. However, these heavy elements are not available in sufficient quantities for conventional chemical studies and so will not be considered further here. Beyond fermium, even the longest-lived isotopes of the elements are highly radioactive, having only short half-lives (e.g. 53 d for Md, 185 s for No and 45 s for Lr). [Pg.5]

The discovery of Pu has been described in detail by Seaborg in his Plutonium Story (chapter 1 of the book The Transuranium Elements 1958). First, the separation of Pu from Th caused some difficulties, because both elements were in the oxidation state 4-4. After oxidation of Pu(IV) by persulfate to Pu(VI), separation became possible. Pu is produced in appreciable amounts in nuclear reactors (section 14.1), but it has not immediately been detected, due to its low specific activity caused by its long half-life. After the discovery of Pu, plutonium gained great practical importance, because of the high fission cross section of Pu by thermal neutrons. Very small amounts of Pu are present in uranium ores, due to (n, y) reaction of neutrons from cosmic radiation with The ratio Pu/ U is of the order of 10 In 1971, the longest-lived isotope of plutonium, Pu (ri/2 = 8.00 lO y) was found by Hoffman in the Ce-rich rare-earth mineral bastnaesite, in concentrations of the order of 10 gAg-... [Pg.285]

The half-lives of the longest-lived isotopes of transuranium elements (Fig. 14.8) show a continuous exponential decrease with increasing atomic number Z. Whereas up to element 103 the half-life is mainly determined by a decay, the influence of spontaneous fission seems to become predominant for elements with Z > 106. The drop model of nuclei predicts a continuous decrease of the fission barrier from about 6 MeV for uranium to about zero for element 110. That means that according to the drop model, elements with Z > 110 are not expected to exist, because normal vibrations of the nuclei should lead to fission. [Pg.292]

Figure 14.8. a-decay (o) and spontaneous fission (x) half-lives of the longest-lived isotopes of heavy elements. [Pg.293]

Fig. 1. The longest-lived isotopes of transuranium elements as a function of Z for spontaneous fission and a decay (11)... Fig. 1. The longest-lived isotopes of transuranium elements as a function of Z for spontaneous fission and a decay (11)...

See other pages where Element 112 longest-lived isotopes is mentioned: [Pg.226]    [Pg.365]    [Pg.8]    [Pg.312]    [Pg.130]    [Pg.729]    [Pg.778]    [Pg.786]    [Pg.948]    [Pg.123]    [Pg.263]    [Pg.419]    [Pg.274]    [Pg.973]    [Pg.282]    [Pg.2]    [Pg.226]    [Pg.226]    [Pg.2]    [Pg.295]    [Pg.92]    [Pg.8]    [Pg.3087]   
See also in sourсe #XX -- [ Pg.55 ]




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