Isotopes of praseodymium

Naturally occurring praseodymium (Pr) is composed of one stable isotope, ¹⁴¹Pr. Thirty-eight radioisotopes have been characterized with the most stable being ¹⁴³Pr, with a half-life of 13.57 days and ¹⁴²Pr, with a half-life of 19.12 hours. All of the remaining radioactive isotopes have half-lives that are less than 5.985 hours and the majority of these have half-lives that are less than 33 seconds. This element also has 15 meta states with the most stable being ^138mPr (t_1/2 2.12 hours), ^142mPr (t_1/2 14.6 minutes) and ^134mPr (t_1/2 11 minutes).

The isotopes of praseodymium range in atomic weight from 120.955 u (¹²¹Pr) to 158.955 u (¹⁵⁹Pr). The primary decay mode before the stable isotope, ¹⁴¹Pr, is electron capture and the mode after is beta decay. The primary decay products before ¹⁴¹Pr are element 58 (cerium) isotopes and the primary products after are element 60 (neodymium) isotopes.

Relative atomic mass: 140.90766(2).^[1]

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)[2][n 1]	daughter isotope(s)[n 2]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^121Pr	59	62	120.95536(75)#	600(300) ms	p	^120Ce	(3/2−)
					β^+ (rare)	^121Ce
					β^+, p (rare)	^120La
^122Pr	59	63	121.95181(54)#	500# ms	β^+	^122Ce
^123Pr	59	64	122.94596(64)#	800# ms	β^+	^123Ce	3/2+#
^124Pr	59	65	123.94296(64)#	1.2(2) s	β^+	^124Ce
					β^+, p (rare)	^123La
^125Pr	59	66	124.93783(43)#	3.3(7) s	β^+	^125Ce	3/2+#
					β^+, p (rare)	^124La
^126Pr	59	67	125.93531(21)#	3.12(18) s	β^+	^126Ce	(4,5,6)
					β^+, p (rare)	^125La
^127Pr	59	68	126.93083(21)#	4.2(3) s	β^+	^127Ce	3/2+#
^127mPr	600(200)# keV			50# ms			11/2−
^128Pr	59	69	127.92879(3)	2.84(9) s	β^+	^128Ce	(3+)
					β^+, p (rare)	^127La
^129Pr	59	70	128.92510(3)	32(3) s	β^+	^129Ce	(11/2−)
^129mPr	382.7(5) keV			1# ms	β^+	^129Ce	(11/2−)
^130Pr	59	71	129.92359(7)	40.0(4) s	β^+	^130Ce	(6,7)(+#)
^130mPr	100(100)# keV			10# s			2+#
^131Pr	59	72	130.92026(6)	1.50(3) min	β^+	^131Ce	(3/2+)
^131mPr	152.4(2) keV			5.7(2) s	IT (96.4%)	^131Pr	(11/2−)
					β^+ (3.59%)	^131Ce
^132Pr	59	73	131.91926(6)	1.49(11) min	β^+	^132Ce	(2+)
^132mPr	0(100)# keV			20# s	β^+	^132Ce	(5+)
^133Pr	59	74	132.916331(13)	6.5(3) min	β^+	^133Ce	(3/2+)
^133mPr	192.05(14) keV			1.1(2) µs			(11/2−)
^134Pr	59	75	133.91571(4)	~11 min	β^+	^134Ce	(5−)
^134mPr	0(100)# keV			17(2) min	β^+	^134Ce	2−
^135Pr	59	76	134.913112(13)	24(2) min	β^+	^135Ce	3/2(+)
^135mPr	358.06(6) keV			105(10) µs			(11/2−)
^136Pr	59	77	135.912692(13)	13.1(1) min	β^+	^136Ce	2+
^137Pr	59	78	136.910705(13)	1.28(3) h	β^+	^137Ce	5/2+
^137mPr	561.22(23) keV			2.66(7) µs			11/2−
^138Pr	59	79	137.910755(15)	1.45(5) min	β^+	^138Ce	1+
^138mPr	348(23) keV			2.12(4) h	β^+	^138Ce	7−
^139Pr	59	80	138.908938(8)	4.41(4) h	β^+	^139Ce	5/2+
^140Pr	59	81	139.909076(7)	3.39(1) min	β^+	^140Ce	1+
^140m1Pr	127.5(3) keV			0.35(2) µs			5+
^140m2Pr	763.3(7) keV			3.05(20) µs			(8)−
^141Pr[n 3]	59	82	140.9076528(26)	Stable[n 4]			5/2+	1.0000
^142Pr	59	83	141.9100448(26)	19.12(4) h	β^− (99.98%)	^142Nd	2−
					EC (.0164%)	^142Ce
^142mPr	3.694(3) keV			14.6(5) min	IT	^142Pr	5−
^143Pr[n 3]	59	84	142.9108169(28)	13.57(2) d	β^−	^143Nd	7/2+
^144Pr	59	85	143.913305(4)	17.28(5) min	β^−	^144Nd	0−
^144mPr	59.03(3) keV			7.2(3) min	IT (99.93%)	^144Pr	3−
					β^− (.07%)	^144Nd
^145Pr	59	86	144.914512(8)	5.984(10) h	β^−	^145Nd	7/2+
^146Pr	59	87	145.91764(7)	24.15(18) min	β^−	^146Nd	(2)−
^147Pr	59	88	146.918996(25)	13.4(4) min	β^−	^147Nd	(3/2+)
^148Pr	59	89	147.922135(28)	2.29(2) min	β^−	^148Nd	1−
^148mPr	50(30)# keV			2.01(7) min	β^−	^148Nd	(4)
^149Pr	59	90	148.92372(9)	2.26(7) min	β^−	^149Nd	(5/2+)
^150Pr	59	91	149.926673(28)	6.19(16) s	β^−	^150Nd	(1)−
^151Pr	59	92	150.928319(25)	18.90(7) s	β^−	^151Nd	(3/2)(−#)
^152Pr	59	93	151.93150(13)	3.63(12) s	β^−	^152Nd	4+
^153Pr	59	94	152.93384(11)	4.28(11) s	β^−	^153Nd	5/2−#
^154Pr	59	95	153.93752(16)	2.3(1) s	β^−	^154Nd	(3+,2+)
^155Pr	59	96	154.94012(32)#	1# s [>300 ns]	β^−	^155Nd	5/2−#
^156Pr	59	97	155.94427(43)#	500# ms [>300 ns]	β^−	^156Nd
^157Pr	59	98	156.94743(43)#	300# ms	β^−	^157Nd	5/2−#
^158Pr	59	99	157.95198(64)#	200# ms	β^−	^158Nd
^159Pr	59	100	158.95550(75)#	100# ms	β^−	^159Nd	5/2−#

1. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
3. Fission product
4. Theoretically capable of spontaneous fission

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. Table of Standard Atomic Weights 2013 – CIAAW
2. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
• 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; 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.
  • 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. 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; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. 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 978-0-8493-0485-9.