77 because many of the transuranic elements are

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[77] Because many of the transuranic elements are highly unstable and decay quickly, they are challenging to detect and characterize when produced. There have been controversies concerning the acceptance of competing discovery claims for some elements, requiring independent review to determine which party has priority, and hence naming rights. The most recently accepted and named elements are flerovium (element 114) and livermorium (element 116), both named on 31 May 2012. [78] In 2010, a joint Russia–US collaboration at Dubna, Moscow Oblast, Russia, claimed to have synthesized six atoms of ununseptium (element 117), making it the most recently claimed discovery. [79] Alternative layouts Main article: Alternative periodic tables There are many periodic tables with layouts other than that of the common or standard form. Within 100 years of the appearance of Mendeleev's table in 1869 it has been estimated that around 700 different periodic table versions were published. [80] As well as numerous rectangular variations, other periodic table formats have included, for example, [n 7] circular, cubic, cylindrical, edificial (building-like), helical, lemniscate (http://cultureofchemistry.fieldofscience.com/2009/03/weird-words-of-science-lemniscate.html), octagonal prismatic, pyramidal, separated, spherical, spiral, and triangular forms. Such alternatives are often developed to highlight or emphasize chemical or physical properties of the elements that are not as apparent in traditional periodic tables. [80] A popular [81] alternative layout is that of Theodor Benfey (1960). The elements are arranged in a continuous spiral, with hydrogen at the center and the transition metals, lanthanides, and actinides occupying peninsulas. [82]
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6/2/13 11:44 AM Periodic table - Wikipedia, the free encyclopedia Page 11 of 17 http://en.wikipedia.org/wiki/Periodic_table V · T · E (//en.wikipedia.org/w/index.php?title=Template:Janet_left-step_periodic_table_(with_shell_filling_sequence)&action=edit) Most periodic tables are two-dimensional [3] however three-dimensional tables are known to as far back as at least 1862 (pre-dating Mendeleev's two-dimensional table of 1869). More recent examples include Courtines' Periodic Classification (1925), [83] Wringley's Lamina System (1949), [84] Giguère's Periodic helix (1965) [85][n 8] and Dufour's Periodic Tree (1996). [86] Going one better, Stowe's Physicist's Periodic Table (1989) [87] has been described as being four-dimensional (having three spatial and one colour dimension). [88] The various forms of periodic tables can be thought of as lying on a chemistry–physics continuum. [89] Towards the chemistry end of the continuum can be found, as an example, Rayner-Canham's 'unruly' [90] Inorganic Chemist's Periodic Table (2002), [91] which emphasizes trends and patterns, and unusual chemical relationships and properties. Near the physics end of the continuum is Janet's Left-Step Periodic Table (1928). This has a structure which shows a closer connection to the order of electron-shell filling and, by association, quantum mechanics.
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