Isotopes of radium

Ra-226 nitrate (3x 1 mCi) - Photo by Dr Andrew R. Burgoyne - Oak Ridge National Laboratory

Ra-224 nitrate (21.4 mCi) - Photo by Dr Andrew R. Burgoyne - Oak Ridge National Laboratory

Main isotopes^[1]			Decay
abundance	half-life (t_1/2)	mode	product
²²³Ra	trace	11.43 d	α	²¹⁹Rn
²²⁴Ra	trace	3.6319 d	α	²²⁰Rn
²²⁵Ra	trace	14.9 d	β⁻	²²⁵Ac
²²⁵Ra	trace	14.9 d	α^[2]	²²¹Rn
²²⁶Ra	trace	1599 y	α	²²²Rn
²²⁸Ra	trace	5.75 y	β⁻	²²⁸Ac

Radium (₈₈Ra) has no stable or nearly stable isotopes, and thus a standard atomic weight 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 decay chain of ²³⁸U (often referred to as the radium series). Radium has 34 known isotopes from ²⁰¹Ra to ²³⁴Ra.

In the early history of the study of radioactivity, the different natural isotopes of radium were given different names, as it was not until Frederick Soddy's scientific career in the early 1900s that the concept of isotopes was realized.^[3] In this scheme, ²²³Ra was named actinium X (AcX), ²²⁴Ra thorium X (ThX), ²²⁶Ra radium (Ra), and ²²⁸Ra mesothorium 1 (MsTh₁).^[4] When it was realized that all of these are isotopes of the same element, many of these names fell out of use, and "radium" came to refer to all isotopes, not just ²²⁶Ra,^[5] though mesothorium 1 in particular was still used for some time, with a footnote explaining that it referred to ²²⁸Ra.^[6] Some of radium-226's decay products received historical names including "radium",^[7] ranging from radium A to radium G, with the letter indicating approximately how far they were down the chain from their parent ²²⁶Ra.^[a]

In 2013 it was discovered that the nucleus of radium-224 is pear-shaped.^[10] This was the first discovery of an asymmetrical nucleus.

List of isotopes

[edit ]

Nuclide ^{[n 1]}	Historic name	Z	N	Isotopic mass (Da)^[11] ^{[n 2]}^{[n 3]}	Half-life ^[1]	Decay mode ^[1] ^{[n 4]}	Daughter isotope ^{[n 5]}	Spin and parity ^[1] ^{[n 6]}^{[n 7]}	Isotopic abundance
Nuclide ^{[n 1]}	Historic name	Excitation energy^{[n 7]}			Half-life ^[1]	Decay mode ^[1] ^{[n 4]}	Daughter isotope ^{[n 5]}	Spin and parity ^[1] ^{[n 6]}^{[n 7]}	Isotopic abundance
²⁰¹Ra	88	113	201.012815(22)	20(30) ms	α	¹⁹⁷Rn	(3/2−)
^201mRa	263(26) keV			6(5) ms	α	¹⁹⁷Rn	13/2+
²⁰²Ra	88	114	202.009742(16)	4.1(11) ms	α	¹⁹⁸Rn	0+
²⁰³Ra	88	115	203.009234(10)	36(13) ms	α	¹⁹⁹Rn	3/2−
^203mRa	246(14) keV			25(5) ms	α	¹⁹⁹Rn	13/2+
²⁰⁴Ra	88	116	204.0065069(96)	60(9) ms	α (99.7%)	²⁰⁰Rn	0+
²⁰⁵Ra	88	117	205.006231(24)	220(50) ms	α	²⁰¹Rn	3/2−
^205mRa	263(25) keV			180(50) ms	α	²⁰¹Rn	13/2+
²⁰⁶Ra	88	118	206.003828(19)	0.24(2) s	α	²⁰²Rn	0+
²⁰⁷Ra	88	119	207.003772(63)	1.38(18) s	α (86%)	²⁰³Rn	5/2−#
²⁰⁷Ra	88	119	207.003772(63)	1.38(18) s	β⁺ (14%)	²⁰⁷Fr	5/2−#
^207mRa	560(60) keV			57(8) ms	IT (85#%)	²⁰⁷Ra	13/2+
^207mRa	560(60) keV			57(8) ms	α (?%)	²⁰³Rn	13/2+
²⁰⁸Ra	88	120	208.0018550(97)	1.110(45) s	α (87%)	²⁰⁴Rn	0+
²⁰⁸Ra	88	120	208.0018550(97)	1.110(45) s	β⁺ (13%)	²⁰⁸Fr	0+
^208mRa	2147.4(4) keV			263(17) ns	IT	²⁰⁸Ra	(8+)
²⁰⁹Ra	88	121	209.0019949(62)	4.71(8) s	α (90%)	²⁰⁵Rn	5/2−
^209mRa	882.4(7) keV			117(5) μs	α (90%)	²⁰⁵Rn	13/2+
^209mRa	882.4(7) keV			117(5) μs	β⁺ (10%)	²⁰⁹Fr	13/2+
²¹⁰Ra	88	122	210.0004754(99)	4.0(1) s	α	²⁰⁶Rn	0+
^210mRa	2050.9(7) keV			2.29(3) μs	IT	²¹⁰Ra	8+
²¹¹Ra	88	123	211.0008930(53)	12.6(12) s	α	²⁰⁷Rn	5/2−
^211mRa	1198.1(8) keV			9.5(3) μs	IT	²¹¹Ra	13/2+
²¹²Ra	88	124	211.999787(11)	13.0(2) s	α (?%)	²⁰⁸Rn	0+
²¹²Ra	88	124	211.999787(11)	13.0(2) s	β⁺ (?%)	²¹²Fr	0+
^212m1Ra	1958.4(20) keV			9.3(9) μs	IT	²¹²Ra	8+
^212m2Ra	2613.3(20) keV			0.85(13) μs	IT	²¹²Ra	11−
²¹³Ra	88	125	213.000371(11)	2.73(5) min	α (87%)	²⁰⁹Rn	1/2−
²¹³Ra	88	125	213.000371(11)	2.73(5) min	β⁺ (13%)	²¹³Fr	1/2−
^213mRa	1768(4) keV			2.20(5) ms	IT (99.4%)	²¹³Ra	(17/2−)
^213mRa	1768(4) keV			2.20(5) ms	α (0.6%)	²⁰⁹Rn	(17/2−)
²¹⁴Ra	88	126	214.0000996(56)	2.437(16) s	α (99.94%)	²¹⁰Rn	0+
²¹⁴Ra	88	126	214.0000996(56)	2.437(16) s	β⁺ (0.059%)	²¹⁴Fr	0+
^214m1Ra	1819.7(18) keV			118(7) ns	IT	²¹⁴Ra	6+
^214m2Ra	1865.2(18) keV			67.3(15) μs	IT (99.91%)	²¹⁴Ra	8+
^214m2Ra	1865.2(18) keV			67.3(15) μs	α (0.09%)	²¹⁰Rn	8+
^214m3Ra	2683.2(18) keV			295(7) ns	IT	²¹⁴Ra	11−
^214m4Ra	3478.4(18) keV			279(4) ns	IT	²¹⁴Ra	14+
^214m5Ra	4146.8(18) keV			225(4) ns	IT	²¹⁴Ra	17−
^214m6Ra	6577.0(18) keV			128(4) ns	IT	²¹⁴Ra	(25−)
²¹⁵Ra	88	127	215.0027182(77)	1.669(9) ms	α	²¹¹Rn	9/2+#
^215m1Ra	1877.8(3) keV			7.31(13) μs	IT	²¹⁵Ra	(25/2+)
^215m2Ra	2246.9(4) keV			1.39(7) μs	IT	²¹⁵Ra	(29/2−)
^215m3Ra	3807(50)# keV			555(10) ns	IT	²¹⁵Ra	(43/2−)
²¹⁶Ra	88	128	216.0035335(86)	172(7) ns	α	²¹²Rn	0+
²¹⁶Ra	88	128	216.0035335(86)	172(7) ns	EC (&l×ばつ10⁻⁸%)	²¹⁶Fr	0+
²¹⁷Ra	88	129	217.0063227(76)	1.95(12) μs	α	²¹³Rn	(9/2+)
²¹⁸Ra	88	130	218.007134(11)	25.91(14) μs	α	²¹⁴Rn	0+
²¹⁹Ra	88	131	219.0100847(73)	9(2) ms	α	²¹⁵Rn	(7/2)+
^219mRa	16.7(8) keV			10(3) ns	α	²¹⁵Rn	(11/2)+
²²⁰Ra	88	132	220.0110275(82)	18.1(12) ms	α	²¹⁶Rn	0+
²²¹Ra	88	133	221.0139173(05)	25(4) s	α	²¹⁷Rn	5/2+	Trace^{[n 8]}
²²¹Ra	88	133	221.0139173(05)	25(4) s	CD (×ばつ10⁻¹⁰%)^{[n 9]}	²⁰⁷Pb ¹⁴C	5/2+	Trace^{[n 8]}
²²²Ra	88	134	222.0153734(48)	33.6(4) s	α	²¹⁸Rn	0+
²²²Ra	88	134	222.0153734(48)	33.6(4) s	CD (×ばつ10⁻⁸%)	²⁰⁸Pb ¹⁴C	0+
²²³Ra ^{[n 10]}	Actinium X	88	135	223.0185006(22)	11.4352(10) d	α	²¹⁹Rn	3/2+	Trace^{[n 11]}
²²³Ra ^{[n 10]}	Actinium X	88	135	223.0185006(22)	11.4352(10) d	CD (×ばつ10⁻⁸%)	²⁰⁹Pb ¹⁴C	3/2+	Trace^{[n 11]}
²²⁴Ra	Thorium X	88	136	224.0202104(19)	3.6316(14) d	α	²²⁰Rn	0+	Trace^{[n 12]}
²²⁴Ra	Thorium X	88	136	224.0202104(19)	3.6316(14) d	CD (×ばつ10⁻⁹%)	²¹⁰Pb ¹⁴C	0+	Trace^{[n 12]}
²²⁵Ra	88	137	225.0236105(28)	14.82(19) d	β⁻	²²⁵Ac	1/2+	Trace^{[n 13]}
²²⁵Ra	88	137	225.0236105(28)	14.82(19) d	α (×ばつ10⁻³%)^[2]	²²¹Rn	1/2+	Trace^{[n 13]}
²²⁶Ra	Radium^{[n 14]}	88	138	226.0254082(21)	1600(7) y	α^{[n 15]}	²²²Rn	0+	Trace^{[n 16]}
²²⁶Ra	Radium^{[n 14]}	88	138	226.0254082(21)	1600(7) y	CD (×ばつ10⁻⁹%)	²¹²Pb ¹⁴C	0+	Trace^{[n 16]}
²²⁷Ra	88	139	227.0291762(21)	42.2(5) min	β⁻	²²⁷Ac	3/2+
²²⁸Ra	Mesothorium 1	88	140	228.0310686(21)	5.75(3) y	β⁻	²²⁸Ac	0+	Trace^{[n 12]}
²²⁹Ra	88	141	229.034957(17)	4.0(2) min	β⁻	²²⁹Ac	5/2+
²³⁰Ra	88	142	230.037055(11)	93(2) min	β⁻	²³⁰Ac	0+
²³¹Ra	88	143	231.041027(12)	104(1) s	β⁻	²³¹Ac	(5/2+)
^231mRa	66.21(9) keV			~53 μs	IT	²³¹Ra	(1/2+)
²³²Ra	88	144	232.0434753(98)	4.0(3) min	β⁻	²³²Ac	0+
²³³Ra	88	145	233.0475946(92)	30(5) s	β⁻	²³³Ac	1/2+#
²³⁴Ra	88	146	234.0503821(90)	30(10) s	β⁻	²³⁴Ac	0+
This table header & footer: view

^ ^mRa – Excited nuclear isomer.
^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
^ Modes of decay:
EC: Electron capture

CD: Cluster decay

IT: Isomeric transition
^ Bold symbol as daughter – Daughter product is stable.
^ ( ) spin value – Indicates spin with weak assignment arguments.
^ ^a ^b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
^ Intermediate decay product of ²³⁷Np
^ Lightest known nuclide to undergo cluster decay
^ Used for treating bone cancer
^ Intermediate decay product of ²³⁵U
^ ^a ^b Intermediate decay product of ²³²Th
^ Intermediate decay product of ²³⁷Np
^ Source of element's name
^ Theoretically capable of β⁻β⁻ decay to ²²⁶Th
^ Intermediate decay product of ²³⁸U

Actinides vs fission products

[edit ]

Actinides and fission products by half-life v t e
Actinides ^[12] by decay chain				Half-life range (a)	Fission products of ²³⁵U by yield ^[13]
4n	4n + 1	4n + 2	4n + 3	Half-life range (a)	4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^No	4–6 a	¹⁵⁵Eu^þ
²⁴⁸Bk^[14]	> 9 a
²⁴⁴Cm^ƒ	²⁴¹Pu^ƒ	²⁵⁰Cf	²²⁷Ac^No	10–29 a	⁹⁰Sr	⁸⁵Kr	^113mCd^þ
²³²U^ƒ	²³⁸Pu^ƒ	²⁴³Cm^ƒ	29–97 a	¹³⁷Cs	¹⁵¹Sm^þ	^121mSn
²⁴⁹Cf^ƒ	^242mAm^ƒ	141–351 a	No fission products have a half-life in the range of 100 a–210 ka ...
²⁴¹Am^ƒ	²⁵¹Cf^ƒ^[15]	430–900 a
²²⁶Ra^No	²⁴⁷Bk	1.3–1.6 ka
²⁴⁰Pu	²²⁹Th	²⁴⁶Cm^ƒ				²⁴³Am^ƒ	4.7–7.4 ka
²⁴⁵Cm^ƒ	²⁵⁰Cm	8.3–8.5 ka
²³⁹Pu^ƒ	24.1 ka
²³⁰Th^No	²³¹Pa^No	32–76 ka
²³⁶Np^ƒ	²³³U^ƒ	²³⁴U^No	150–250 ka	⁹⁹Tc^₡	¹²⁶Sn
²⁴⁸Cm	²⁴²Pu	327–375 ka	⁷⁹Se^₡
1.33 Ma	¹³⁵Cs^₡
²³⁷Np^ƒ	1.61–6.5 Ma	⁹³Zr	¹⁰⁷Pd
²³⁶U	²⁴⁷Cm^ƒ	15–24 Ma	¹²⁹I^₡
²⁴⁴Pu	80 Ma	... nor beyond 15.7 Ma^[16]
²³²Th^No	²³⁸U^No	... nor beyond 15.7 Ma^[16]			²³⁵U^ƒNo	0.7–14.1 Ga
₡, has thermal neutron capture cross section in the range of 8–50 barns ƒ, fissile No, primarily a naturally occurring radioactive material (NORM) þ, neutron poison (thermal neutron capture cross section greater than 3k barns)

References

[edit ]

^ ^a ^b ^c ^d Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
^ ^a ^b Liang, C. F.; Paris, P.; Sheline, R. K. (2000年09月19日). "α decay of ²²⁵Ra". Physical Review C. 62 (4). American Physical Society (APS): 047303. Bibcode:2000PhRvC..62d7303L. doi:10.1103/physrevc.62.047303. ISSN 0556-2813.
^ Nagel, Miriam C. (September 1982). "Frederick Soddy: From alchemy to isotopes". Journal of Chemical Education. 59 (9): 739. Bibcode:1982JChEd..59..739N. doi:10.1021/ed059p739. ISSN 0021-9584.
^ Kirby, H.W. & Salutsky, Murrell L. (December 1964). The Radiochemistry of Radium (Report). crediting UNT Libraries Government Documents Department. p. 3 – via University of North Texas, UNT Digital Library. Alternate source: https://sgp.fas.org/othergov/doe/lanl/lib-www/books/rc000041.pdf
^ Giunta, Carmen J. (2017). "ISOTOPES: IDENTIFYING THE BREAKTHROUGH PUBLICATION (1)" (PDF). Bull. Hist. Chem. 42 (2): 103–111.
^ Looney, William B. (1958). "Effects of Radium in Man". Science. 127 (3299): 630–633. Bibcode:1958Sci...127..630L. doi:10.1126/science.127.3299.630. ISSN 0036-8075. JSTOR 1755774. PMID 13529029.
^ Mitchell, S. A. "Is Radium in the Sun?". Popular Astronomy. 21: 321–331. Bibcode:1913PA.....21..321M.
^ Kuhn, W. (1929). "LXVIII. Scattering of thorium C" γ-radiation by radium G and ordinary lead". The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science. 8 (52): 628. doi:10.1080/14786441108564923. ISSN 1941-5982.
^ Kinsey, R. R. (December 18, 1997), "The radioactive series of radium-226" (PDF), The NUDAT/PCNUDAT Program for Nuclear Data – via CERN
^ Hills, Stephanie (8 May 2013). "First observations of short-lived pear-shaped atomic nuclei". CERN.
^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
^ 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 nuclides have half-lives of at least four years (the longest-lived nuclide 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 uranium-235, e.g. in a typical nuclear reactor.
^ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
"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 [years]. No growth of Cf²⁴⁸ was detected, and a lower limit for the β⁻ half-life can be set at about 10⁴ [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]."
^ This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
^ Excluding those "classically stable" nuclides with half-lives significantly in excess of ²³²Th; e.g., while ^113mCd has a half-life of only fourteen years, that of ¹¹³Cd is eight quadrillion years.

Isotope masses from:
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.200311001
Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.200311001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

Notes

[edit ]

^ Radium emanation = ²²²Rn, Ra A = ²¹⁸Po, Ra B = ²¹⁴Pb, Ra C = ²¹⁴Bi, Ra C₁ = ²¹⁴Po, Ra C₂ = ²¹⁰Tl, Ra D = ²¹⁰Pb, Ra E = ²¹⁰Bi, Ra F = ²¹⁰Po, and Ra G = ²⁰⁶Pb.^[8]^[9]

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