Isotopes of hassium

Hassium (Hs) 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 ²⁶⁵Hs in 1984. There are 12 known isotopes from ²⁶³Hs to ²⁷⁷Hs and 1-4 isomers. The longest-lived isotope is ²⁶⁹Hs with a half-life of 9.6 seconds.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^{[n 1]}	daughter isotope(s)	nuclear spin
nuclide symbol	excitation energy			half-life	decay mode(s)^{[n 1]}	daughter isotope(s)	nuclear spin
²⁶³Hs	108	155	263.12856(37)#	1# ms	α	²⁵⁹Sg	7/2+#
²⁶⁴Hs	108	156	264.12839(5)	540(300) µs	α (50%)	²⁶⁰Sg	0+
²⁶⁴Hs	108	156	264.12839(5)	540(300) µs	SF (50%)	(various)	0+
²⁶⁵Hs	108	157	265.13009(15)#	2.1(3) ms [2.0(+3-2) ms]	α	²⁶¹Sg	9/2+#
^265mHs	300(70) keV			0.780(0.15) ms [0.75(+17-12) ms]	α	²⁶¹Sg	3/2+#
²⁶⁶Hs^{[n 2]}	108	158	266.13010(31)#	2.7(10) ms [2.3(+13-6) ms]	α	²⁶²Sg	0+
²⁶⁷Hs	108	159	267.13179(11)#	52(+13-8) s ms	α	²⁶³Sg	3/2+#
^267mHs^{[n 3]}					α	²⁶³Sg
²⁶⁸Hs	108	160	268.13216(44)#	2# s	α	²⁶⁴Sg	0+
²⁶⁹Hs^{[n 4]}	108	161	269.13406(13)#	9.7(+99-33) s	α	²⁶⁵Sg
^269mHs^{[n 3]}					α	²⁶⁵Sg
²⁷⁰Hs	108	162	270.13465(31)#	3.6(+8-14) s	α	²⁶⁶Sg	0+
²⁷¹Hs	108	163	271.13766(36)#	40# s	α	²⁶⁷Sg
²⁷³Hs^{[n 5]}	108	165	273.14199(89)#	240 ms	α	²⁶⁹Sg	(3/2+)#
²⁷⁵Hs^{[n 6]}	108	167	275.14595(77)#	0.15(+27-6) s	α	²⁷¹Sg
²⁷⁷Hs^{[n 7]}	108	169	277.14984(78)#		SF	(various)	3/2+#
^277mHs^{[n 3]}^{[n 7]}				40(30) min	SF	(various)

^ Abbreviations:
SF: Spontaneous fission
^ Not directly synthesized, occurs as decay product of ²⁷⁰Ds
^ ^a ^b ^c Existence of this isomer is unconfirmed
^ Not directly synthesized, occurs in decay chain of ²⁷⁷Cn
^ Not directly synthesized, occurs in decay chain of ²⁸⁵Uuq
^ Not directly synthesized, occurs in decay chain of ²⁸⁷Uuq
^ ^a ^b Not directly synthesized, occurs in decay chain of ²⁸⁹Uuq

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

National Nuclear Data Center, Brookhaven National Laboratory
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 bohrium	Isotopes of hassium	Isotopes of meitnerium
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