Islands of stability

Fig. 7. Allegorical representation of island of stability (magic island) (28).

Since the radioactive half-lives of the known transuranium elements and their resistance to spontaneous fission decrease with increase in atomic number, the outlook for the synthesis of further elements might appear increasingly bleak. However, theoretical calculations of nuclear stabilities, based on the concept of closed nucleon shells (p. 13) suggest the existence of an island of stability around Z= 114 and N= 184. Attention has therefore been directed towards the synthesis of element 114 (a congenor of Pb in Group 14 and adjacent superheavy elements, by bombardment of heavy nuclides with a wide range of heavy ions, but so far without success. 

Uneven open shell Pn clusters are easier to ionize than even closed shell ones and the stability of the closed shell uneven P cluster cations is higher. For very large Pn+ cations with n = 25 + 8x (x — 0.1.2. 8) islands of stability were observed in the time of flight mass spectrum (TOF-MS) obtained by laser ablation of red phosphorus, suggesting that the more stable P clusters have connections with units of eight P atoms [71d]. A lot of effort has been put into the calculation of the most stable Pn+ cation structures. The respective global minimum structures of the more stable uneven P3+, Ps+, P71 and P<)h cluster cations are shown in Figure 2.6-10 [73, 74],... 

In this book the superactinide elements begin at Z-114 because this is the first element that was recognized in what is known as the island of stability, also referred to as the Island of Nuclear Stability. The stability of Z-114 is related to its exceptional long half-life of 30 seconds, which provides adequate time for detection and research on it. It also appears that the heavier the element, the shorter its half-life. 

Element 114 is the first element in the group referred to as the island of stability, which consists of element 114 to the optimum element 184. The elements in this so-called island of stability all have a rather stable arrangement of neutrons and protons in their nuclei and a similar configuration of the electrons in their orbits (shells) that result in longer half-lives than some of the SHE elements not located in the island. ... 

A joint Russian and American team of physicists created two new super heavy elements—115 and 113—that provide more support for the island of stability concept. The experiments were conducted between July 14 and August 10 in 2003, but the results of the experiments were not published until February 2004. The experiments were conducted in the Joint Institute of Nuclear Research (JINR) in Dubna, Russia, and also involved the scientists of the Lawrence Berkely National Laboratory located at Berkeley, California. Only four atoms of two isotopes of ununpentium (element 115) were produced, and the results were published in a peer-reviewed scientific journal. Following is the nuclear reaction that produced these four atoms ... 

Because element 117 (ununseptium) has not yet been produced, its properties are not known. This does not hinder speculation as to what some of the properties and characteristics of jj Uus will be when it is discovered and where it will fit into the scheme of what is known of elements 116 and 118—if they are confirmed. One thing that can be assumed with a high degree of probability is that Uus does not have a magic number of protons and neutrons, and thus is not included as one of the elements in the island of stability. ... 

Aliens on Earth, http //www.ufomind.com/misc/1999/jun/dl0-001.shtml (accessed October 24, 2005). Answers.com. http //www.answers.com/topic/creating-elements hl = element hl =112 (accessed October 20, 2005). Answers.com. http ///www.answers.com/topic/island-of-stability.html (accessed October 23> 2005). 

The Free Dictionary Island of Stability, http //encyclopedia.thefreedictionary.com/ Island+of+stability (accessed... 

Superheavy Elements Island of Stability. LBNL Image Library. http //www.imglib.Ibl.gov. ImgLib/COLLECTlONS/ BERKELEY-LAB/SEABORG-ARCHIVE (accessed October 23, 2005). 

Investigation of physical and chemical properties of recently synthesized, relatively long-living isotopes of superheavy elements (SHEs) with nuclear charges Z=105 to 116 [1, 2, 3, 4] and their compounds is of fundamental importance. Their measured lifetimes may reach several hours and the nuclei near the top of the island of stability are predicted to exist for many years. The experimental study of the SHE properties is very difficult be-... 

Stable isotopes prefer a certain combination of neutrons and protons. By far, most stable isotopes have an even number of both protons and neutrons. A smaller number of stable isotopes have either an even number of protons and an odd number of neutrons or vice-versa, and only a few have both an odd number of protons and neutrons (Table 17.1). Stable nuclei are also associated with a speciflc number of protons or neutrons. These islands of stability occur when the number of protons or neutrons is 2, 8, 20, 28, 50, 82, and 126. To illustrate this, consider tin with an atomic number of 50. Tin has ten stable isotopes, but antimony with an atomic number of 51 has only two. 

One isotope of element 114, with 184 neutrons, is predicted to be another doubly magic nucleus, and is therefore expected to sit right in the middle of an island of stability in the space of superheavy nuclei (Fig. 13). Nuclear scientists suspect that it may have a half-life of as much as several years. Element 114 has thus become a kind of Holy Grail for element-makers. If it turns out to be stable, this would show that these researchers are not necessarily doomed to search for increasingly fleeting glimpses of ever heavier and less stable new elements. There might be undiscovered elements out there that you can (in principle, at least) hold in your hand. 

The isotope of element 114 with 184 neutrons is predicted to be especially stable, since it has magic numbers of both protons and neutrons in its nuclei. This element may sit atop an island of stability in the sea of possible combinations of subatomic nuclear particles. Other islands, here picked out in contours whose height denotes the degree of stability, occur for lighter elements such as some isotopes of lead and tin... 

But how does one get to the centre of the putative island of stability, where the doubly magic isotope of element 114 resides This means sticking more neutrons onto the nucleus, and no one yet knows how to do that. 

A brief and good account of the manufacture of superheavy elements, and the search for the island of stability. Is given by R. Stone, Science, 278 (1997), 571, and Science, 283 (1999), 474. The topic is discussed in more detail in G. T. Seaborg and W. D. Loveland, The search for new elements . In N. Hall (ed.). The New Chemistry (Cambridge Cambridge University Press,... 

It can be seen that elements in and near the island of stability based on element 114 can be predicted to have chemical properties as follows element 114 should be a homologue of lead, that is, should be eka-lead and element 112 should be eka-mercury, element 110 should be eka-platinum, etc. If there is an island of stability at element 126, this element and its neighbors should have chemical properties like those of the actinide and lanthanide elements. 

We now know these predictions were wrong, in part. While we believe there are a group of superheavy nuclei whose half-lives are relatively long compared to lower Z elements, we do not believe they form an island of stability. Rather, we picture them as a continuation of the peninsula of known nuclei (Fig. 15.1 lb). We also believe that their half-lives are short compared to geologic time scales. Therefore, they do not exist in nature. The most stable of the superheavy nuclei, those with Z = 112, N 184, are predicted to decay by a-particle emission with half-lives of 20 days. 

The "island of stability" near 114 protons and 184 neutrons corresponds to a group of superheavy nuclei that are predicted to be stable. The first member of this group was reported in 1999. 

When the more than 3600 known nuclides are plotted on the neutron/proton grid in Figure 22.3, they fall in a curved band sometimes called the "band of nuclear stability." Even within the band, only 264 of the nuclides are stable indefinitely. The remainder decay spontaneously, although their rates of decay vary enormously. On either side of the band is a "sea of instability" representing the large number of unstable neutron/proton combinations that have never been seen. Particularly interesting is the "island of stability" predicted to exist for a few superheavy nuclides near 114 protons and 184 neutrons. The first members of this group—287114,288114,289114, and 292116—were prepared in 1999 and do indeed seem to be unusually stable. Isotope 289114, for example, has a half-life of 30.4 seconds. 

Island of Stability The name given to a possible group of trans-fermian elements where the number of protons and neutrons in the elements nuclei are such that the nuclei are much more stable than other known transfermian elements. 

The Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna, Russia, has recently announced the observation of relatively long-lived isotopes of elements 108, 110, 112, 114, and 116 [63-66] confirming the over 30 years old theoretical prediction of an island of stability of spherical superheavy elements. Due to the half-lives of the observed isotopes in the range of seconds to minutes, chemical investigations of these heaviest elements in the Periodic Table appear now to be feasible. The chemistry of these elements should be extremely interesting due to the predicted dramatic influence of relativistic effects [67], In addition, the chemical identification of the newly discovered superheavy elements is highly desirable as the observed decay chains [63-66] cannot be linked to known nuclides which has been heavily criticized [68,69],... 

The term "superheavy elements" was first coined for elements on a remote "island of stability" around atomic number 114 (Chapter 8). At that time this island of stability was believed to be surrounded by a "sea of instability". By now, as shown in Chapter 1, this sea has drained off and sandbanks and rocky footpaths, paved with cobblestones of shell-stabilized deformed nuclei, are connecting the region of shell-stabilized spherical nuclei around element 114 to our known world. 

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