Isotopes of radium

Actinides and fission products by half-life v t e
Actinides^[1] by decay chain				Half-life range (y)	Fission products of ²³⁵U by yield^[2]
4n	4n+1	4n+2	4n+3		Fission products of ²³⁵U by yield^[2]
4n	4n+1	4n+2	4n+3			4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^№				4–6	†		¹⁵⁵Eu^þ
²⁴⁴Cm	²⁴¹Pu^ƒ	²⁵⁰Cf	²²⁷Ac^№	10–29		⁹⁰Sr	⁸⁵Kr	^113mCd^þ
²³²U^ƒ		²³⁸Pu^№	²⁴³Cm^ƒ	29–97		¹³⁷Cs	¹⁵¹Sm^þ	^121mSn
²⁴⁸Bk^[3]	²⁴⁹Cf^ƒ	^242mAm^ƒ		141–351	No fission products have a half-life in the range of 100–210 k years ...
	²⁴¹Am^ƒ		²⁵¹Cf^ƒ^[4]	430–900
		²²⁶Ra^№	²⁴⁷Bk	1.3 k – 1.6 k
²⁴⁰Pu	²²⁹Th^№	²⁴⁶Cm	²⁴³Am^ƒ	4.7 k – 7.4 k
	²⁴⁵Cm^ƒ	²⁵⁰Cm		8.3 k – 8.5 k
			²³⁹Pu^ƒ№	24.1 k
		²³⁰Th^№	²³¹Pa^№	32 k – 76 k
²³⁶Np^ƒ	²³³U^ƒ№	²³⁴U^№		150 k – 250 k	‡	⁹⁹Tc^₡	¹²⁶Sn
²⁴⁸Cm		²⁴²Pu		327 k – 375 k			⁷⁹Se^₡
				1.53 M		⁹³Zr
	²³⁷Np^№			2.1 M – 6.5 M		¹³⁵Cs^₡	¹⁰⁷Pd
²³⁶U^№			²⁴⁷Cm^ƒ	15 M – 24 M			¹²⁹I^₡
²⁴⁴Pu^№				80 M	... nor beyond 15.7 M years^[5]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7 G – 14.1 G	... nor beyond 15.7 M years^[5]
Legend for superscript symbols ₡ has thermal neutron capture cross section in the range of 8–50 barns ƒ fissile m metastable isomer № naturally occurring radioactive material (NORM) þ neutron poison (thermal neutron capture cross section greater than 3k barns) † range 4–97 y: Medium-lived fission product ‡ over 200,000 y: Long-lived fission product

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 1,600 years. ²²⁶Ra occurs in the decay chain of ²³⁸U (often referred to as the radium series.) Radium has 33 known isotopes from ²⁰²Ra to ²³⁴Ra.

Table

nuclide symbol	historic name	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[6]^{[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)^[6]^{[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+	Trace^{[n 3]}
²²²Ra		88	134	222.015375(5)	38.0(5) s	CD (3×10⁻⁸%)	²⁰⁸Pb ¹⁴C	0+	Trace^{[n 3]}
²²³Ra^{[n 4]}	Actinium X	88	135	223.0185022(27)	11.43(5) d	α	²¹⁹Rn	3/2+	Trace^{[n 5]}
²²³Ra^{[n 4]}	Actinium X	88	135	223.0185022(27)	11.43(5) d	CD (6.4×10⁻⁸%)	²⁰⁹Pb ¹⁴C	3/2+	Trace^{[n 5]}
²²⁴Ra	Thorium X	88	136	224.0202118(24)	3.6319(23) d	α	²²⁰Rn	0+	Trace^{[n 6]}
²²⁴Ra	Thorium X	88	136	224.0202118(24)	3.6319(23) d	CD (4.3×10⁻⁹%)	²¹⁰Pb ¹⁴C	0+	Trace^{[n 6]}
²²⁵Ra		88	137	225.023612(3)	14.9(2) d	β⁻	²²⁵Ac	1/2+
²²⁶Ra	Radium^{[n 7]}	88	138	226.0254098(25)	1600(7) y	α	²²²Rn	0+	^{[n 8]}
						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 6]}
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 ²³⁸U
↑ Used for treating bone cancer
↑ Intermediate decay product of ²³⁵U
↑ ^6.0 ^6.1 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

↑ Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no isotopes have half-lives of at least four years (the longest-lived isotope in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
↑ Specifically from thermal neutron fission of U-235, e.g. in a typical nuclear reactor.
↑ Lua error in package.lua at line 80: module 'strict' not found.
"The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk²⁴⁸ with a half-life greater than 9 y. No growth of Cf²⁴⁸ was detected, and a lower limit for the β⁻ half-life can be set at about 10⁴ y. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 y."
↑ This is the heaviest isotope with a half-life of at least four years before the "Sea of Instability".
↑ Excluding those "classically stable" isotopes with half-lives significantly in excess of ²³²Th; e.g., while ^113mCd has a half-life of only fourteen years, that of ¹¹³Cd is nearly eight quadrillion years.
↑ Lua error in package.lua at line 80: module 'strict' not found.

Isotope masses from:
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Isotopic compositions and standard atomic masses from:
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Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
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Isotopes of francium	Isotopes of radium	Isotopes of actinium
Table of nuclides

[7] Abbreviations:
CD: Cluster decay
EC: Electron capture
IT: Isomeric transition

[8] Bold for stable isotopes

[9] Intermediate decay product of ²³⁸U

[10] Used for treating bone cancer

[11] Intermediate decay product of ²³⁵U

[ths-12] 6.0 ^6.1 Intermediate decay product of ²³²Th

[13] Source of element's name

[14] Intermediate decay product of ²³⁸U

[1] Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no isotopes have half-lives of at least four years (the longest-lived isotope in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.

[2] Specifically from thermal neutron fission of U-235, e.g. in a typical nuclear reactor.

[3] Lua error in package.lua at line 80: module 'strict' not found.
"The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk²⁴⁸ with a half-life greater than 9 y. No growth of Cf²⁴⁸ was detected, and a lower limit for the β⁻ half-life can be set at about 10⁴ y. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 y."

[4] This is the heaviest isotope with a half-life of at least four years before the "Sea of Instability".

[5] Excluding those "classically stable" isotopes with half-lives significantly in excess of ²³²Th; e.g., while ^113mCd has a half-life of only fourteen years, that of ¹¹³Cd is nearly eight quadrillion years.

[6] Lua error in package.lua at line 80: module 'strict' not found.

[1]

[2]

[3]

[4]

[5]

[6]

[n 1]

[n 2]

[n 3]

[n 4]

[n 5]

[n 6]

[n 7]

[n 8]

v t e Isotopes of the chemical elements
1 H																	2 He
3 Li	4 Be											5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg											13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba		72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra		104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Uut	114 Fl	115 Uup	116 Lv	117 Uus	118 Uuo

		57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu
		89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr
Table of nuclides Categories: Isotopes Tables of nuclides Metastable isotopes Isotopes by element

Isotopes of radium

Table

Notes

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