Superactinide elements

The calculations indicate that the 8 subsheU should fiU at elements 119 and 120, thus making these an alkaH and alkaline earth metal, respectively. Next, the calculations point to the filling, after the addition of a 7t7 electron at element 121 of the inner 5 and (if subsheUs, 32 places in aU, which the author has termed the superactinide elements and which terminates at element 153. This is foUowed by the filling of the 7d subsheU (elements 154 through 162) and 8 subsheU (elements 163 through 168). 

The positively charged protons are compacted in a tiny, dense center of the atom called the nucleus. The number of protons in the nucleus determines the atomic number for each element. The periodic table lists the number of protons in progression from the first number, hydrogen (jH, with one proton), to the most recently discovered superactinide elements and yet-to-be-discovered elements with the highest atomic numbers. 

Aetinide metah—includes elements with atomic numbers from 89 to 111. Also includes the transuranic elements (e.g., beyond uranium to lojLr]) and the superactinides (elements with atomic numbers 104 to 118 that are artificial, radioactive, and unstable with very short half-lives). 

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. 

Beyond element 121, eka-actinium, a series of 6f elements may occur, in analogy to the 5/ actinidc elements following actinium. But the 5g orbital -the first g orbital at all - may be filled in competition. Consequently, a series of 32 superactinide elements [20] may exist in which inner electron shells are filled whereas the configuration of the valence electrons remains unchanged. The chemistry of such elements [14,15] would be most exciting. 

Predicted electronic configuration and chemical properties of superactinide elements. 

The next element, number 121, might be termed eka-actinium, or perhaps superactinium (because it is followed by 32 rather than 14 inner transition elements), and the following superactinide elements (numbers 122-153, inclusive) might have chemical properties somewhat similar to, but also different from, the actinide elements. 

There are other series of elements that appear separately in the periodic table, namely the lanthanide series and the actinide series. The superactinide series and the super heavy elements (SHE) are additional series of newly discovered elements. These series of elements are extensions to the normal periodic order of the periodic table. 

The superactinide series begins where the transactinide series ends, usually with the element with atomic number 114, and continues to the element with atomic number 118. 

The transactinide series of elements (Z-104 to Z-113) are those elements that follow the actinide series (Z-89 to Z-103) and proceed to the superactinides, some of which are yet to be discovered. (Note Z is the symbol used to represent the atomic numbers [protons] of elements in the transactinide series, as well as of other elements.) All elements of the transactinide series are radioactive, heavy metals that are unstable, and they usually decay by spontaneous fission or alpha decay into smaller nuclei of elements with less mass. 

Table 4.1 Symbols used in naming elements not yet named or discovered in the actinide, transactinide, and superactinide series of heavy elements.

The Superactinides (Super Heavy Elements) and Possible Future Elements... 

There is some question regarding where the transactinide series ends and where the superactinide series and super heavy elements (also known as SHE) begin. Some references start the superactinides and SHEs at Z-114, Z-123, or Z-126, and others start at Z-141 and continue to Z-153, or even higher to Z-202. These series of elements are characterized by single electrons successively added to inner shells and orbital of the atom until they are fiUed. This is somewhat similar to the way electrons are added to the atoms of the lanthanide and actinide series. 

Transactini(le, Superactinide, and Super Heavy Elements beyond Lawrencium 103 are all made artificially and in minute amounts. All are unstable and radioactive with very short half-lives. 

Note Superactinides and super heavy elements (SHE) are elements beyond lawrencium 103- All are artificially produced, unstable, and radioactive and have very short half-lives. Most are made in small amounts, even one atom at a time. 

Though substantial progress has been reached in understanding the chemistry of the heaviest elements, there is still a number of open questions needed to be answered from both the experimental and theoretical points of view. For the superactinides, investigations of the chemical properties will be even more exciting, since the resemblance of their properties to those of their lighter homologues will be much less pronounced. 

The term superactinides (Fig. 14.16) was introduced in 1968 for the elements with Z > 121. In these elements, the 6f and 5g levels are expected to be filled as indicated in Table 14.8. Four sublevels (8p]/2> 7d3/2, 6f5/2 and 5g7/2) are assumed to compete with each other and to determine, together with the 8s electrons, the properties and the chemistry of these elements. 

The difference in the chemistry of the light and heavy actinides may be rationalized in this way. The early members beyond thorium have unpaired d and / electrons available for forming covalent bonds and hence, for example, they readily form many complex ions and intermetallic compounds. Such ions are soft acids. Beyond americium, the 5/ electrons are not competitive and the closed shell of six 5/5/2 electrons will not be readily available for bonding, so that only those / electrons with /=7/2 are available. These tend to become buried radially as the atomic number increases and hence their divalent ions become relatively hard Lewis acids. These considerations are especially helpful in the region of superactinides because these elements do not have analogs in the known periodic table, where we have deeply buried but loosely bound 5g electrons. 

In the lanthanoides and actinoides, the competition between the outer d and inner / electrons determines the ground-state electron configuration as well as the chemistry of these elements. Here at the beginning of the superactinides, not merely two but four electron shells, namely the 8 1/2, and 5g7/2, are... 

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