Ununseptium (pronEng|ˌjuːnənˈsɛptiəm or IPA|/ˌʌnənˈsɛptiəm/) is the temporary name of an undiscovered chemical element in the periodic table that has the temporary symbol Uus and the atomic number 117. Its half-life presumably will be 3 nanosecondsFact|date=August 2008. It is expected to decay by alpha decay to element 115.

Future experiments

Ununseptium has not yet been discovered. As of March 2008, no attempt to synthesize this element has been reported.

Theoretical calculations in a quantum tunneling model with mass estimates from a macroscopic-microscopic model predict the alpha-decay half-lives of isotopes of the element 117 (namely, 289-303117) to be around 0.1-40 ms. citejournal| journal=Nucl. Phys. A|volume=789|pages=142–154|year=2007| title=Predictions of alpha decay half lives of heavy and superheavy elements|author=C. Samanta, P. Roy Chowdhury and D.N. Basu|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVB-4NF4F0Y-2&_user=2806701&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000058844&_version=1&_urlVersion=0&_userid=2806701&md5=3f680654b5659191d67f31681a4cfc83| doi=10.1016/j.nuclphysa.2007.04.001] [citejournal|journal=Phys. Rev. C|volume=77|pages=044603|year=2008|title=Search for long lived heaviest nuclei beyond the valley of stability|author=P. Roy Chowdhury, C. Samanta, and D. N. Basu|url=http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRVCAN000077000004044603000001&idtype=cvips&gifs=yes|doi=10.1103/PhysRevC.77.044603] [citejournal|journal=At. Data & Nucl. Data Tables|year=2008|title=Nuclear half-lives for α -radioactivity of elements with 100 < Z < 130 |author=P. Roy Chowdhury, C. Samanta, and D. N. Basu|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WBB-4S26JRX-1&_user=2806701&_coverDate=03%2F14%2F2008&_alid=740505626&_rdoc=6&_fmt=high&_orig=search&_cdi=6706&_sort=d&_docanchor=&view=c&_ct=211&_acct=C000058844&_version=1&_urlVersion=0&_userid=2806701&md5=dc85a3a8a2ac1faa38c3804f16f86c13]

Chemical properties

Certain chemical properties, such as bond lengths, are predicted to differ from what one would expect based on periodic trends from the lighter halogens (because of relativistic effects). [cite web | url=http://dirac.chem.sdu.dk/thesis/96.saue_phd.pdf | title=Principles and Applications of Relativistic Molecular Calculations | author=Trond Saue, page 76] Ununseptium may show semimetal properties as well.


The name ununseptium is a systematic element name, used as a placeholder until it is confirmed by other research groups and the IUPAC decides on a name. Usually, the name suggested by the discoverer(s) is chosen.


External links

* [http://webelements.com/ununseptium/ WebElements.com: Uus]

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