הבדלים בין גרסאות בדף "מחצית חיים"

הוסרו 4,677 בתים ,  לפני 3 שנים
|-
! 83
| [[Bismuth]] || <sup>209</sup>Bi || data-sort-value="19,000,000,000,000,000,000"|2 × 10<sup>19</sup> years || [[Isotopes of bismuth]]
|-
! 84
! 118
| [[Ununoctium]] || <sup>294</sup>Uuo || data-sort-value="0.00089"|890 microseconds || [[Isotopes of ununoctium]]
|}
|}<small>(Note that for elements 108–118, the longest-lived known isotope is always the heaviest or second-heaviest (115) discovered thus far. This makes it seem likely that there are longer-lived undiscovered isotopes among the even heavier ones.)</small>
 
For comparison, the shortest-lived element with atomic number below 100 is [[francium]] (element&nbsp;87) with a half-life of 22&nbsp;minutes.
 
The [[half-life|half-lives]] of nuclei in the island of stability itself are unknown since none of the isotopes that would be "on the island" have been observed. Many physicists think they are relatively short, on the order of minutes or days.<ref name=physorg/> Some theoretical calculations indicate that their half-lives may be long, on the order of 10<sup>9</sup>&nbsp;years.<ref>{{cite journal |last=Oganessian |first=Yuri |title=Nuclei in the "Island of Stability" of Superheavy Elements |journal=Journal of Physics: Conference Series |volume=337 |issue=1 |at=012005 |doi=10.1088/1742-6596/337/1/012005|bibcode = 2012JPhCS.337a2005O }}</ref>
 
The alpha-decay half-lives of 1700&nbsp;nuclei with 100&nbsp;≤&nbsp;Z&nbsp;≤&nbsp;130 have been calculated in a quantum tunneling model with both experimental and theoretical alpha-decay Q-values.<ref name="half-lifesall">{{Cite journal|journal=Phys. Rev. C|volume=73|page=014612|date= January 26, 2006 |title=α decay half-lives of new superheavy elements|author1=P. Roy Chowdhury |author2=C. Samanta |author3=D. N. Basu |doi=10.1103/PhysRevC.73.014612|arxiv = nucl-th/0507054 |bibcode = 2006PhRvC..73a4612C }}</ref><ref name="predictions">{{Cite journal|journal=Nucl. Phys. A|volume=789|pages=142–154|year=2007|title=Predictions of alpha decay half lives of heavy and superheavy elements|author1=C. Samanta |author2=P. Roy Chowdhury |author3=D.N. Basu |doi=10.1016/j.nuclphysa.2007.04.001|arxiv = nucl-th/0703086 |bibcode = 2007NuPhA.789..142S }}</ref><ref name="longlived">{{Cite journal|journal=Phys. Rev. C|volume=77|issue=4|page=044603|year=2008|title=Search for long lived heaviest nuclei beyond the valley of stability|author1=P. Roy Chowdhury |author2=C. Samanta |author3=D. N. Basu |doi=10.1103/PhysRevC.77.044603 |url=http://prc.aps.org/abstract/PRC/v77/i4/e044603|bibcode = 2008PhRvC..77d4603C |arxiv = 0802.3837 }}</ref><ref name="nuclear">{{Cite journal|journal=Atomic Data and Nuclear Data Tables|year=2008|title=Nuclear half-lives for α-radioactivity of elements with 100&nbsp;<&nbsp;Z&nbsp;<&nbsp;130|author1=P. Roy Chowdhury |author2=C. Samanta |author3=D. N. Basu |doi=10.1016/j.adt.2008.01.003|volume=94|issue=6|page=781|bibcode = 2008ADNDT..94..781C |arxiv = 0802.4161 }}</ref><ref name="decaychains">{{Cite journal|journal=Phys. Rev. C|volume=75|issue=4|page=047306|date= January 26, 2007 |title=α decay chains from element 113|author1=P. Roy Chowdhury |author2=D. N. Basu |author3=C. Samanta |doi=10.1103/PhysRevC.75.047306|bibcode = 2007PhRvC..75d7306C |arxiv = 0704.3927 }}</ref><ref name="tunneling">{{Cite journal|doi=10.1143/JPSJ.76.124201|title=Quantum tunneling in <sup>277</sup>112 and its alpha-decay chain|author1=Chhanda Samanta |author2=Devasish Narayan Basu |author3=Partha Roy Chowdhury |journal=[[Journal of the Physical Society of Japan]]|year=2007|volume=76|issue=12|pages=124201–124204|bibcode = 2007JPSJ...76l4201S |arxiv = 0708.4355 }}</ref> The theoretical calculations are in good agreement with the available experimental data. {{dubious||E.g. the values for No-260 and {{not a typo|-262}} in <ref name="nuclear"/> are of by ~5 orders of magnitude!|date=July 2012}}
 
A possible stronger decay mode for the heaviest superheavies was shown to be [[cluster decay]] by [[Dorin N. Poenaru]], R.A. Gherghescu, and [[Walter Greiner]].<ref name="cldec">{{Cite journal|journal=Phys. Rev. Lett. |volume=107|issue=6|page=062503|year= 2011 |title= Heavy-Particle Radioactivity of Superheavy Nuclei |author= [[Dorin N Poenaru]], R.A. Gherghescu, [[Walter Greiner]]|doi=10.1103/PhysRevLett.107.062503|bibcode = 2011PhRvL.107f2503P |arxiv = 1106.3271|url=http://link.aps.org/doi/10.1103/PhysRevLett.107.062503|pmid=21902317 }}</ref>
 
[[File:Periodic Table Radioactivity.svg|center|500px|thumb|Periodic table with elements colored according to the half-life of their most stable isotope.
{{legend|cyan|Stable elements.}}
{{legend|lime|Radioactive elements with half-lives of over four million years.}}
{{legend|yellow|Half-lives between 800 and 34,000 years.}}
{{legend|#FF6B00|Half-lives between 1&nbsp;day and 103&nbsp;years.}}
{{legend|red|Half-lives ranging between several minutes and 1&nbsp;day.}}
{{legend|purple|Half-lives less than several minutes.}}]]
 
== ראו גם ==