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Isotopes of protactinium



Protactinium (Pa)
Standard atomic mass: 231.03588(2) u
The element has no stable isotopes. However, it has a characteristic terrestrial isotopic composition and thus an atomic mass can be given.

Additional recommended knowledge

Isotopes of protactinium occurring within the radioactive disintegration chain of uranium were known as:

  • uranium X2 : 234mPa
  • uranium Z : 234Pa

Older named for the element were:

29 radioisotopes of protactinium have been characterized, with the most stable being 231-Pa with a half life of 32760 years, 233-Pa with a half-life of 26.967 days, and 230-Pa with a half-life of 17.4 days. All of the remaining radioactive isotopes have half-lifes that are less than 1.6 days, and the majority of these have half lifes that are less than 1.8 seconds. This element also has 2 meta states, 217m-Pa (t½ 1.15 milliseconds) and 234m-Pa (t½ 1.17 minutes).

The primary decay mode for isotopes of Pa lighter than (and including) the most stable isotope 231-Pa (ie, 212Pa to 231Pa) is alpha decay and the primary mode for the heavier isotopes (ie, 232Pa to 240Pa) is beta minus (β) decay. The primary decay products of isotopes of Pa lighter than (and including) 231-Pa are element Ac (actinium) isotopes and the primary decay products for the heavier isotopes of Pa are element U (uranium) isotopes.

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
212Pa 91 121 212.02320(8) 8(5) ms [5.1(+61-19) ms] 7+#
213Pa 91 122 213.02111(8) 7(3) ms [5.3(+40-16) ms] 9/2-#
214Pa 91 123 214.02092(8) 17(3) ms
215Pa 91 124 215.01919(9) 14(2) ms 9/2-#
216Pa 91 125 216.01911(8) 105(12) ms
217Pa 91 126 217.01832(6) 3.48(9) ms 9/2-#
217mPa 1860(7) keV 1.08(3) ms 29/2+#
218Pa 91 127 218.020042(26) 0.113(1) ms
219Pa 91 128 219.01988(6) 53(10) ns 9/2-
220Pa 91 129 220.02188(6) 780(160) ns 1-#
221Pa 91 130 221.02188(6) 4.9(8) µs 9/2-
222Pa 91 131 222.02374(8)# 3.2(3) ms
223Pa 91 132 223.02396(8) 5.1(6) ms
224Pa 91 133 224.025626(17) 844(19) ms 5-#
225Pa 91 134 225.02613(8) 1.7(2) s 5/2-#
226Pa 91 135 226.027948(12) 1.8(2) min
227Pa 91 136 227.028805(8) 38.3(3) min (5/2-)
228Pa 91 137 228.031051(5) 22(1) h 3+
229Pa 91 138 229.0320968(30) 1.50(5) d (5/2+)
229mPa 11.6(3) keV 420(30) ns 3/2-
230Pa 91 139 230.034541(4) 17.4(5) d (2-)
231Pa 91 140 231.0358840(24) 3.276(11)E+4 a 3/2- 1.0000
232Pa 91 141 232.038592(8) 1.31(2) d (2-)
233Pa 91 142 233.0402473(23) 26.975(13) d 3/2-
234Pa 91 143 234.043308(5) 6.70(5) h 4+
234mPa 78(3) keV 1.17(3) min (0-)
235Pa 91 144 235.04544(5) 24.44(11) min (3/2-)
236Pa 91 145 236.04868(21) 9.1(1) min 1(-)
237Pa 91 146 237.05115(11) 8.7(2) min (1/2+)
238Pa 91 147 238.05450(6) 2.27(9) min (3-)#
239Pa 91 148 239.05726(21)# 1.8(5) h (3/2)(-#)
240Pa 91 149 240.06098(32)# 2# min

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

  • Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
  • Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
  • Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
    • Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
    • National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
    • David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.


Isotopes of thorium Isotopes of protactinium Isotopes of uranium
Index to isotope pages
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Isotopes_of_protactinium". A list of authors is available in Wikipedia.
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