Isotopes of radium

Radium (Ra) has no stable isotopes. A standard atomic mass cannot be given. The longest lived, and most common, isotope of radium is ²²⁶Ra which occurs in the disintegration chain of ²³⁸U (often referred to as the radium series.)

Isotopes of radium occurring within the radioactive disintegration chains of actinium and thorium were known as

actinium X, ²²³Ra
thorium X, ²²⁴Ra
mesothorium I, ²²⁸Ra

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)
nuclide symbol	excitation energy			half-life	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	(3/2-)
^203mRa	220(90) keV			41(17) ms	(13/2+)
²⁰⁴Ra	88	116	204.006500(17)	60(11) ms [59(+12-9) ms]	0+
²⁰⁵Ra	88	117	205.00627(9)	220(40) ms [210(+60-40) ms]	(3/2-)
^205mRa	310(110)# keV			180(50) ms [170(+60-40) ms]	(13/2+)
²⁰⁶Ra	88	118	206.003827(19)	0.24(2) s	0+
²⁰⁷Ra	88	119	207.00380(6)	1.3(2) s	(5/2-,3/2-)
^207mRa	560(50) keV			57(8) ms	(13/2+)
²⁰⁸Ra	88	120	208.001840(17)	1.3(2) s	0+
^208mRa	1800(200) keV			270 ns	(8+)
²⁰⁹Ra	88	121	209.00199(5)	4.6(2) s	5/2-
²¹⁰Ra	88	122	210.000495(16)	3.7(2) s	0+
^210mRa	1800(200) keV			2.24 µs	(8+)
²¹¹Ra	88	123	211.000898(28)	13(2) s	5/2(-)
²¹²Ra	88	124	211.999794(12)	13.0(2) s	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	1/2-
^213mRa	1769(6) keV			2.1(1) ms	17/2-#
²¹⁴Ra	88	126	214.000108(10)	2.46(3) s	0+
²¹⁵Ra	88	127	215.002720(8)	1.55(7) ms	(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	0+
²¹⁷Ra	88	129	217.006320(9)	1.63(17) µs	(9/2+)
²¹⁸Ra	88	130	218.007140(12)	25.2(3) µs	0+
²¹⁹Ra	88	131	219.010085(9)	10(3) ms	(7/2)+
²²⁰Ra	88	132	220.011028(10)	17.9(14) ms	0+
²²¹Ra	88	133	221.013917(5)	28(2) s	5/2+
²²²Ra	88	134	222.015375(5)	38.0(5) s	0+
²²³Ra	88	135	223.0185022(27)	11.43(5) d	3/2+
²²⁴Ra	88	136	224.0202118(24)	3.6319(23) d	0+
²²⁵Ra	88	137	225.023612(3)	14.9(2) d	1/2+
²²⁶Ra	88	138	226.0254098(25)	1600(7) y	0+
²²⁷Ra	88	139	227.0291778(25)	42.2(5) min	3/2+
²²⁸Ra	88	140	228.0310703(26)	5.75(3) y	0+
²²⁹Ra	88	141	229.034958(20)	4.0(2) min	5/2(+)
²³⁰Ra	88	142	230.037056(13)	93(2) min	0+
²³¹Ra	88	143	231.04122(32)#	103(3) s	(5/2+)
^231mRa	66.21(9) keV			~53 µs	(1/2+)
²³²Ra	88	144	232.04364(30)#	250(50) s	0+
²³³Ra	88	145	233.04806(50)#	30(5) s	1/2+#
²³⁴Ra	88	146	234.05070(53)#	30(10) s	0+

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.