Isotopes of meitnerium

Meitnerium (Mt) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was ²⁶⁶Mt in 1982 (this is also the only isotope directly synthesized, all other isotopes are decay products of heavier elements). There are seven known isotopes, from ²⁶⁶Mt to ²⁷⁸Mt. There may also be two isomers. The longest-lived of the known isotopes is ²⁷⁸Mt with a half-life of 8 seconds.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin
	excitation energy
266Mt	109	157	266.13730(37)#	1.2(4) ms	α	262Bh
268Mt[n 1]	109	159	268.13873(34)#	21(+8-5) ms	α	264Bh	5+#,6+#
268mMt[n 2]	0+X keV			0.07(+10-3) s	α	264Bh
270Mt[n 3]	109	161	270.14066(58)#	2# s	α	266Bh
270mMt[n 2]					α	266Bh
274Mt[n 4]	109	165	274.14749(60)#	20# s	α	270Bh
275Mt[n 5]	109	166	275.14865(64)#	9.7(+460-44) ms	α	271Bh
276Mt[n 6]	109	167	276.15116(73)#	0.72(+87-25) s	α	272Bh
278Mt[n 7]	109	169	278.15481(90)#	7.6 s[1]	α	274Bh

1. ^ Not directly synthesized, occurs as decay product of ²⁷²Rg
2. ^ ^{a b} This isomer is unconfirmed
3. ^ Not directly synthesized, occurs in decay chain of ²⁷⁸Uut
4. ^ Not directly synthesized, occurs in decay chain of ²⁸²Uut
5. ^ Not directly synthesized, occurs in decay chain of ²⁸⁷Uup
6. ^ Not directly synthesized, occurs in decay chain of ²⁸⁸Uup
7. ^ Not directly synthesized, occurs in decay chain of ²⁹⁴Uus

Notes

• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

1. ^ Oganessian, Yu. Ts.; Abdullin, F. Sh.; Bailey, P. D.; Benker, D. E.; Bennett, M. E.; Dmitriev, S. N.; Ezold, J. G.; Hamilton, J. H. et al. (2010). "Synthesis of a New Element with Atomic Number Z=117". Physical Review Letters 104. Bibcode 2010PhRvL.104n2502O. doi:10.1103/PhysRevLett.104.142502. PMID 20481935. 

• Isotope masses from:
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683. http://www.iupac.org/publications/pac/75/6/0683/pdf/. 
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary. 
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005. 
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859. 

Isotopes of hassium	Isotopes of meitnerium	Isotopes of darmstadtium
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