Isotopes of radium

Radium (Ra) has no stable or nearly stable isotopes, and thus a standard atomic mass cannot be given. The longest lived, and most common, isotope of radium is ²²⁶Ra with a half-life of 1600 years. ²²⁶Ra occurs in the disintegration chain of ²³⁸U (often referred to as the radium series.) Radium has 35 known isotopes from ²⁰¹Ra to ²³⁵Ra, with the newest being ²³⁵Ra.

Table

nuclide symbol	historic name	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)^{[n 2]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	historic name	excitation energy			half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)^{[n 2]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
²⁰²Ra		88	114	202.00989(7)	2.6(21) ms [0.7(+33-3) ms]			0+
²⁰³Ra		88	115	203.00927(9)	4(3) ms	α	¹⁹⁹Rn	(3/2-)
²⁰³Ra		88	115	203.00927(9)	4(3) ms	β⁺ (rare)	²⁰³Fr	(3/2-)
^203mRa		220(90) keV			41(17) ms	α	¹⁹⁹Rn	(13/2+)
^203mRa		220(90) keV			41(17) ms	β⁺ (rare)	²⁰³Fr	(13/2+)
²⁰⁴Ra		88	116	204.006500(17)	60(11) ms [59(+12-9) ms]	α (99.7%)	²⁰⁰Rn	0+
²⁰⁴Ra		88	116	204.006500(17)	60(11) ms [59(+12-9) ms]	β⁺ (.3%)	²⁰⁴Fr	0+
²⁰⁵Ra		88	117	205.00627(9)	220(40) ms [210(+60-40) ms]	α	²⁰¹Rn	(3/2-)
²⁰⁵Ra		88	117	205.00627(9)	220(40) ms [210(+60-40) ms]	β⁺ (rare)	²⁰⁵Fr	(3/2-)
^205mRa		310(110)# keV			180(50) ms [170(+60-40) ms]	α	²⁰¹Rn	(13/2+)
^205mRa		310(110)# keV			180(50) ms [170(+60-40) ms]	IT (rare)	²⁰⁵Ra	(13/2+)
²⁰⁶Ra		88	118	206.003827(19)	0.24(2) s	α	²⁰²Rn	0+
²⁰⁷Ra		88	119	207.00380(6)	1.3(2) s	α (90%)	²⁰³Rn	(5/2-,3/2-)
²⁰⁷Ra		88	119	207.00380(6)	1.3(2) s	β⁺ (10%)	²⁰⁷Fr	(5/2-,3/2-)
^207mRa		560(50) keV			57(8) ms	IT (85%)	²⁰⁷Ra	(13/2+)
						α (15%)	²⁰³Rn
						β⁺ (.55%)	²⁰⁷Fr
²⁰⁸Ra		88	120	208.001840(17)	1.3(2) s	α (95%)	²⁰⁴Rn	0+
²⁰⁸Ra		88	120	208.001840(17)	1.3(2) s	β⁺ (5%)	²⁰⁸Fr	0+
^208mRa		1800(200) keV			270 ns			(8+)
²⁰⁹Ra		88	121	209.00199(5)	4.6(2) s	α (90%)	²⁰⁵Rn	5/2-
²⁰⁹Ra		88	121	209.00199(5)	4.6(2) s	β⁺ (10%)	²⁰⁹Fr	5/2-
²¹⁰Ra		88	122	210.000495(16)	3.7(2) s	α (96%)	²⁰⁶Rn	0+
²¹⁰Ra		88	122	210.000495(16)	3.7(2) s	β⁺ (4%)	²¹⁰Fr	0+
^210mRa		1800(200) keV			2.24 µs			(8+)
²¹¹Ra		88	123	211.000898(28)	13(2) s	α (97%)	²⁰⁷Rn	5/2(-)
²¹¹Ra		88	123	211.000898(28)	13(2) s	β⁺ (3%)	²¹¹Fr	5/2(-)
²¹²Ra		88	124	211.999794(12)	13.0(2) s	α (85%)	²⁰⁸Rn	0+
²¹²Ra		88	124	211.999794(12)	13.0(2) s	β⁺ (15%)	²¹²Fr	0+
^212m1Ra		1958.4(5) keV			10.9(4) µs			(8)+
^212m2Ra		2613.4(5) keV			0.85(13) µs			(11)-
²¹³Ra		88	125	213.000384(22)	2.74(6) min	α (80%)	²⁰⁹Rn	1/2-
²¹³Ra		88	125	213.000384(22)	2.74(6) min	β⁺ (20%)	²¹³Fr	1/2-
^213mRa		1769(6) keV			2.1(1) ms	IT (99%)	²¹³Ra	17/2-#
^213mRa		1769(6) keV			2.1(1) ms	α (1%)	²⁰⁹Rn	17/2-#
²¹⁴Ra		88	126	214.000108(10)	2.46(3) s	α (99.94%)	²¹⁰Rn	0+
²¹⁴Ra		88	126	214.000108(10)	2.46(3) s	β⁺ (.06%)	²¹⁴Fr	0+
²¹⁵Ra		88	127	215.002720(8)	1.55(7) ms	α	²¹¹Rn	(9/2+)#
^215m1Ra		1877.8(5) keV			7.1(2) µs			(25/2+)
^215m2Ra		2246.9(5) keV			1.39(7) µs			(29/2-)
^215m3Ra		3756.6(6)+X keV			0.555(10) µs			(43/2-)
²¹⁶Ra		88	128	216.003533(9)	182(10) ns	α	²¹²Rn	0+
²¹⁶Ra		88	128	216.003533(9)	182(10) ns	EC (1×10⁻⁸%)	²¹⁶Fr	0+
²¹⁷Ra		88	129	217.006320(9)	1.63(17) µs	α	²¹³Rn	(9/2+)
²¹⁸Ra		88	130	218.007140(12)	25.2(3) µs	α	²¹⁴Rn	0+
²¹⁸Ra		88	130	218.007140(12)	25.2(3) µs	β⁺β⁺ (rare)	²¹⁸Rn	0+
²¹⁹Ra		88	131	219.010085(9)	10(3) ms	α	²¹⁵Rn	(7/2)+
²²⁰Ra		88	132	220.011028(10)	17.9(14) ms	α	²¹⁶Rn	0+
²²¹Ra		88	133	221.013917(5)	28(2) s	α	²¹⁷Rn	5/2+
²²¹Ra		88	133	221.013917(5)	28(2) s	CD (1.2×10⁻¹⁰%)	²⁰⁷Pb ¹⁴C	5/2+
²²²Ra		88	134	222.015375(5)	38.0(5) s	α	²¹⁸Rn	0+
²²²Ra		88	134	222.015375(5)	38.0(5) s	CD (3×10⁻⁸%)	²⁰⁸Pb ¹⁴C	0+
²²³Ra	Actinium X	88	135	223.0185022(27)	11.43(5) d	α	²¹⁹Rn	3/2+	Trace^{[n 3]}
²²³Ra	Actinium X	88	135	223.0185022(27)	11.43(5) d	CD (6.4×10⁻⁸%)	²⁰⁹Pb ¹⁴C	3/2+	Trace^{[n 3]}
²²⁴Ra	Thorium X	88	136	224.0202118(24)	3.6319(23) d	α	²²⁰Rn	0+	Trace^{[n 4]}
²²⁴Ra	Thorium X	88	136	224.0202118(24)	3.6319(23) d	CD (4.3×10⁻⁹%)	²¹⁰Pb ¹⁴C	0+	Trace^{[n 4]}
²²⁵Ra		88	137	225.023612(3)	14.9(2) d	β^-	²²⁵Ac	1/2+
²²⁶Ra	Radium^{[n 5]}	88	138	226.0254098(25)	1600(7) y	α	²²²Rn	0+	Trace^{[n 6]}
						β^-β^- (rare)	²²⁶Th
						CD (2.6×10⁻⁹%)	²¹²Pb ¹⁴C
²²⁷Ra		88	139	227.0291778(25)	42.2(5) min	β^-	²²⁷Ac	3/2+
²²⁸Ra	Mesothorium 1	88	140	228.0310703(26)	5.75(3) y	β^-	²²⁸Ac	0+	Trace^{[n 4]}
²²⁹Ra		88	141	229.034958(20)	4.0(2) min	β^-	²²⁹Ac	5/2(+)
²³⁰Ra		88	142	230.037056(13)	93(2) min	β^-	²³⁰Ac	0+
²³¹Ra		88	143	231.04122(32)#	103(3) s	β^-	²³¹Ac	(5/2+)
^231mRa		66.21(9) keV			~53 µs			(1/2+)
²³²Ra		88	144	232.04364(30)#	250(50) s	β^-	²³²Ac	0+
²³³Ra		88	145	233.04806(50)#	30(5) s	β^-	²³³Ac	1/2+#
²³⁴Ra		88	146	234.05070(53)#	30(10) s	β^-	²³⁴Ac	0+

^ Abbreviations:
CD: Cluster decay
EC: Electron capture
IT: Isomeric transition
^ Bold for stable isotopes
^ Intermediate decay product of ²³⁵U
^ ^a ^b Intermediate decay product of ²³²Th
^ Source of element's name
^ Intermediate decay product of ²³⁸U

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

^ http://www.nucleonica.net/unc.aspx

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 francium	Isotopes of radium	Isotopes of actinium
Index to isotope pages · Table of nuclides