Isotopes of promethium

Isotopes of promethium (₆₁Pm)
α	141Pr
β−	146Sm
	view ; talk ; edit ;

Last updated October 11, 2024

Promethium (₆₁Pm) is an artificial element, except in trace quantities as a product of spontaneous fission of ²³⁸U and ²³⁵U and alpha decay of ¹⁵¹Eu, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. It was first synthesized in 1945.

Forty-one radioisotopes have been characterized, with the most stable being ¹⁴⁵Pm with a half-life of 17.7 years, ¹⁴⁶Pm with a half-life of 5.53 years, and ¹⁴⁷Pm with a half-life of 2.6234 years. All of the remaining radioactive isotopes have half-lives that are less than 365 days, and the majority of these have half-lives that are less than 30 seconds. This element also has 18 meta states with the most stable being ^148mPm (t_1/2 41.29 days), ^152m2Pm (t_1/2 13.8 minutes) and ^152mPm (t_1/2 7.52 minutes).

The isotopes of promethium range in mass number from 126 to 166. The primary decay mode for ¹⁴⁶Pm and lighter isotopes is electron capture, and the primary mode for heavier isotopes is beta decay. The primary decay products before ¹⁴⁶Pm are isotopes of neodymium, and the primary products after are isotopes of samarium.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da) ^{[n 2]}^{[n 3]}	Half-life ^{[n 4]}	Decay mode ^{[n 5]}	Daughter isotope ^{[n 6]}^{[n 7]}	Spin and parity ^{[n 8]}^{[n 4]}	Isotopic abundance
Nuclide ^{[n 1]}	Excitation energy^{[n 4]}			Half-life ^{[n 4]}	Decay mode ^{[n 5]}	Daughter isotope ^{[n 6]}^{[n 7]}	Spin and parity ^{[n 8]}^{[n 4]}	Isotopic abundance
¹²⁶Pm	61	65	125.95752(54)#	0.5# s
¹²⁷Pm	61	66	126.95163(64)#	1# s			5/2+#
¹²⁸Pm	61	67	127.94842(43)#	1.0(3) s	β⁺	¹²⁸Nd	6+#
¹²⁸Pm	61	67	127.94842(43)#	1.0(3) s	p	¹²⁷Nd	6+#
¹²⁹Pm	61	68	128.94316(43)#	3# s [>200 ns]	β⁺	¹²⁹Nd	5/2+#
¹³⁰Pm	61	69	129.94045(32)#	2.6(2) s	β⁺	¹³⁰Nd	(5+, 6+, 4+)
¹³⁰Pm	61	69	129.94045(32)#	2.6(2) s	β⁺, p (rare)	¹²⁹Pr	(5+, 6+, 4+)
¹³¹Pm	61	70	130.93587(21)#	6.3(8) s	β⁺, p	¹³⁰Pr	5/2+#
¹³¹Pm	61	70	130.93587(21)#	6.3(8) s	β⁺	¹³¹Nd	5/2+#
¹³²Pm	61	71	131.93375(21)#	6.2(6) s	β⁺	¹³²Nd	(3+)
¹³²Pm	61	71	131.93375(21)#	6.2(6) s	β⁺, p (5×10⁻⁵%)	¹³¹Pr	(3+)
¹³³Pm	61	72	132.92978(5)	15(3) s	β⁺	¹³³Nd	(3/2+)
^133mPm	130.4(10) keV			10# s	β⁺	¹³³Nd	(11/2−)
^133mPm	130.4(10) keV			10# s	IT	¹³³Pm	(11/2−)
¹³⁴Pm	61	73	133.92835(6)	22(1) s	β⁺	¹³⁴Nd	(5+)
^134mPm	0(100)# keV			~5 s	IT	¹³⁴Pm	(2+)
¹³⁵Pm	61	74	134.92488(6)	49(3) s	β⁺	¹³⁵Nd	(5/2+, 3/2+)
^135mPm	50(100)# keV			40(3) s	β⁺	¹³⁵Nd	(11/2−)
¹³⁶Pm	61	75	135.92357(8)	107(6) s	β⁺	¹³⁶Nd	(5−)
^136mPm	130(120) keV			47(2) s	β⁺	¹³⁶Nd	(2+)
¹³⁷Pm	61	76	136.920479(14)	2# min	β⁺	¹³⁷Nd	5/2+#
^137mPm	150(50) keV			2.4(1) min	β⁺	¹³⁷Nd	11/2−
¹³⁸Pm	61	77	137.919548(30)	10(2) s	β⁺	¹³⁸Nd	1+#
^138mPm	30(30) keV			3.24(5) min	β⁺	¹³⁸Nd	5−#
¹³⁹Pm	61	78	138.916804(14)	4.15(5) min	β⁺	¹³⁹Nd	(5/2)+
^139mPm	188.7(3) keV			180(20) ms	IT (99.83%)	¹³⁹Pm	(11/2)−
^139mPm	188.7(3) keV			180(20) ms	β⁺ (0.17%)	¹³⁹Nd	(11/2)−
¹⁴⁰Pm	61	79	139.91604(4)	9.2(2) s	β⁺	¹⁴⁰Nd	1+
^140mPm	420(40) keV			5.95(5) min	β⁺	¹⁴⁰Nd	8−
¹⁴¹Pm	61	80	140.913555(15)	20.90(5) min	β⁺	¹⁴¹Nd	5/2+
^141m1Pm	628.40(10) keV			630(20) ns			11/2−
^141m2Pm	2530.9(5) keV			>2 μs
¹⁴²Pm	61	81	141.912874(27)	40.5(5) s	β⁺	¹⁴²Nd	1+
^142mPm	883.17(16) keV			2.0(2) ms	IT	¹⁴²Pm	(8)−
¹⁴³Pm	61	82	142.910933(4)	265(7) d	EC	¹⁴³Nd	5/2+
¹⁴³Pm	61	82	142.910933(4)	265(7) d	β⁺ (<5.7×10⁻⁶%)^[1]	¹⁴³Nd	5/2+
¹⁴⁴Pm	61	83	143.912591(3)	363(14) d	EC	¹⁴⁴Nd	5−
¹⁴⁴Pm	61	83	143.912591(3)	363(14) d	β⁺ (<8×10⁻⁵%)^[1]	¹⁴⁴Nd	5−
^144m1Pm	840.90(5) keV			780(200) ns			(9)+
^144m2Pm	8595.8(22) keV			~2.7 μs			(27+)
¹⁴⁵Pm	61	84	144.912749(3)	17.7(4) y	EC	¹⁴⁵Nd	5/2+
¹⁴⁵Pm	61	84	144.912749(3)	17.7(4) y	α (2.8×10⁻⁷%)	¹⁴¹Pr	5/2+
¹⁴⁶Pm	61	85	145.914696(5)	5.53(5) y	EC (66%)	¹⁴⁶Nd	3−
¹⁴⁶Pm	61	85	145.914696(5)	5.53(5) y	β⁻ (34%)	¹⁴⁶Sm	3−
¹⁴⁷Pm^{[n 9]}	61	86	146.9151385(26)	2.6234(2) y	β⁻	¹⁴⁷Sm	7/2+	Trace^{[n 10]}
¹⁴⁸Pm	61	87	147.917475(7)	5.368(2) d	β⁻	¹⁴⁸Sm	1−
^148mPm	137.9(3) keV			41.29(11) d	β⁻ (95%)	¹⁴⁸Sm	5−, 6−
^148mPm	137.9(3) keV			41.29(11) d	IT (5%)	¹⁴⁸Pm	5−, 6−
¹⁴⁹Pm^{[n 9]}	61	88	148.918334(4)	53.08(5) h	β⁻	¹⁴⁹Sm	7/2+
^149mPm	240.214(7) keV			35(3) μs			11/2−
¹⁵⁰Pm	61	89	149.920984(22)	2.68(2) h	β⁻	¹⁵⁰Sm	(1−)
¹⁵¹Pm^{[n 9]}	61	90	150.921207(6)	28.40(4) h	β⁻	¹⁵¹Sm	5/2+
¹⁵²Pm	61	91	151.923497(28)	4.12(8) min	β⁻	¹⁵²Sm	1+
^152m1Pm	140(90) keV			7.52(8) min			4−
^152m2Pm	250(150)# keV			13.8(2) min			(8)
¹⁵³Pm	61	92	152.924117(12)	5.25(2) min	β⁻	¹⁵³Sm	5/2−
¹⁵⁴Pm	61	93	153.92646(5)	1.73(10) min	β⁻	¹⁵⁴Sm	(0, 1)
^154mPm	120(120) keV			2.68(7) min	β⁻	¹⁵⁴Sm	(3, 4)
¹⁵⁵Pm	61	94	154.92810(3)	41.5(2) s	β⁻	¹⁵⁵Sm	(5/2−)
¹⁵⁶Pm	61	95	155.93106(4)	26.70(10) s	β⁻	¹⁵⁶Sm	4−
¹⁵⁷Pm	61	96	156.93304(12)	10.56(10) s	β⁻	¹⁵⁷Sm	(5/2−)
¹⁵⁸Pm	61	97	157.93656(14)	4.8(5) s	β⁻	¹⁵⁸Sm
¹⁵⁹Pm	61	98	158.93897(21)#	1.648+0.43 −0.42 s^[2]	β⁻	¹⁵⁹Sm	5/2−#
¹⁶⁰Pm	61	99	159.94299(32)#	874+16 −12 ms^[2]	β⁻	¹⁶⁰Sm
¹⁶¹Pm	61	100	160.94586(54)#	724+20 −12 ms^[2]	β⁻ (98.91%)	¹⁶¹Sm	5/2−#
¹⁶¹Pm	61	100	160.94586(54)#	724+20 −12 ms^[2]	β⁻, n (1.09%)	¹⁶⁰Sm	5/2−#
¹⁶²Pm	61	101	161.95029(75)#	467+38 −18 ms^[2]	β⁻ (98.21%)	¹⁶²Sm
¹⁶²Pm	61	101	161.95029(75)#	467+38 −18 ms^[2]	β⁻, n (1.79%)	¹⁶¹Sm
¹⁶³Pm	61	102	162.95368(86)#	362+42 −30 ms^[2]	β⁻ (95%)	¹⁶³Sm	5/2−#
¹⁶³Pm	61	102	162.95368(86)#	362+42 −30 ms^[2]	β⁻, n (1.79%)	¹⁶²Sm	5/2−#
¹⁶⁴Pm	61	103		280+38 −33 ms^[2]	β⁻ (93.82%)	¹⁶⁴Sm
¹⁶⁴Pm	61	103		280+38 −33 ms^[2]	β⁻, n (6.18%)	¹⁶³Sm
¹⁶⁵Pm	61	104		297+111 −101 ms^[2]	β⁻ (86.74%)	¹⁶⁵Sm
¹⁶⁵Pm	61	104		297+111 −101 ms^[2]	β⁻, n (13.26%)	¹⁶⁴Sm
¹⁶⁶Pm	61	105		228+131 −112 ms^[2]	β⁻	¹⁶⁶Sm
¹⁶⁶Pm	61	105		228+131 −112 ms^[2]	β⁻, n	¹⁶⁵Sm
This table header & footer: view

↑ ^mPm – 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).
1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
↑ Modes of decay:
EC: Electron capture
IT: Isomeric transition
p: Proton emission
↑ Bold italics symbol as daughter – Daughter product is nearly stable.
↑ Bold symbol as daughter – Daughter product is stable.
↑ ( ) spin value – Indicates spin with weak assignment arguments.
1 2 3 Fission product
↑ Spontaneous fission product of ²³²Th, ²³⁵U, ²³⁸U and alpha decay daughter of primordial ¹⁵¹Eu

Stability of promethium isotopes

Promethium is one of the two elements of the first 82 elements that has no stable isotopes. This is a rarely occurring effect of the liquid drop model. Namely, promethium does not have any beta-stable isotopes, as for any mass number, it is energetically favorable for a promethium isotope to undergo positron emission or beta decay, respectively forming a neodymium or samarium isotope which has a higher binding energy per nucleon. The other element for which this happens is technetium (Z = 43).

Promethium-147

Promethium-147 has a half-life of 2.62 years, and is a fission product produced in nuclear reactors via beta decay from neodymium-147. The isotopes ¹⁴²Nd, ¹⁴³Nd, ¹⁴⁴Nd, ¹⁴⁵Nd, ¹⁴⁶Nd, ¹⁴⁸Nd, and ¹⁵⁰Nd are all stable with respect to beta decay, so the isotopes of promethium with those masses cannot be produced by beta decay and therefore are not fission products in significant quantities (they could only be produced directly, rather than along a beta-decay chain). ¹⁴⁹Pm and ¹⁵¹Pm have half-lives of only 53.08 and 28.40 hours, so are not found in spent nuclear fuel that has been cooled for months or years. It is found naturally mostly from the spontaneous fission of uranium-238 and less often from the alpha decay of europium-151.^[3]

Promethium-147 is used as a beta particle source and a radioisotope thermoelectric generator (RTG) fuel; its power density is about 2 watts per gram. Mixed with a phosphor, it was used to illuminate Apollo Lunar Module electrical switch tips and painted on control panels of the Lunar Roving Vehicle.^[4]

Related Research Articles

Protactinium (₉₁Pa) has no stable isotopes. The four naturally occurring isotopes allow a standard atomic weight to be given.

Francium (₈₇Fr) has no stable isotopes. A standard atomic weight cannot be given. Its most stable isotope is ²²³Fr with a half-life of 22 minutes, occurring in trace quantities in nature as an intermediate decay product of ²³⁵U.

There are 39 known isotopes of radon (₈₆Rn), from ¹⁹³Rn to ²³¹Rn; all are radioactive. The most stable isotope is ²²²Rn with a half-life of 3.823 days, which decays into ²¹⁸
Po. Six isotopes of radon, ^{217, 218, 219, 220, 221, 222}Rn, occur in trace quantities in nature as decay products of, respectively, ²¹⁷At, ²¹⁸At, ²²³Ra, ²²⁴Ra, ²²⁵Ra, and ²²⁶Ra. ²¹⁷Rn and ²²¹Rn are produced in rare branches in the decay chain of trace quantities of ²³⁷Np; ²²²Rn is an intermediate step in the decay chain of ²³⁸U; ²¹⁹Rn is an intermediate step in the decay chain of ²³⁵U; and ²²⁰Rn occurs in the decay chain of ²³²Th.

Astatine (₈₅At) has 41 known isotopes, all of which are radioactive; their mass numbers range from 188 to 229. There are also 24 known metastable excited states. The longest-lived isotope is ²¹⁰At, which has a half-life of 8.1 hours; the longest-lived isotope existing in naturally occurring decay chains is ²¹⁹At with a half-life of 56 seconds.

There are 42 isotopes of polonium (₈₄Po). They range in size from 186 to 227 nucleons. They are all radioactive. ²¹⁰Po with a half-life of 138.376 days has the longest half-life of any naturally-occurring isotope of polonium and is the most common isotope of polonium. It is also the most easily synthesized polonium isotope. ²⁰⁹Po, which does not occur naturally, has the longest half-life of all isotopes of polonium at 124 years. ²⁰⁹Po can be made by using a cyclotron to bombard bismuth with protons, as can ²⁰⁸Po.

Thallium (₈₁Tl) has 41 isotopes with atomic masses that range from 176 to 216. ²⁰³Tl and ²⁰⁵Tl are the only stable isotopes and ²⁰⁴Tl is the most stable radioisotope with a half-life of 3.78 years. ²⁰⁷Tl, with a half-life of 4.77 minutes, has the longest half-life of naturally occurring Tl radioisotopes. All isotopes of thallium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

Naturally occurring terbium (₆₅Tb) is composed of one stable isotope, ¹⁵⁹Tb. Thirty-seven radioisotopes have been characterized, with the most stable being ¹⁵⁸Tb with a half-life of 180 years, ¹⁵⁷Tb with a half-life of 71 years, and ¹⁶⁰Tb with a half-life of 72.3 days. All of the remaining radioactive isotopes have half-lives that are less than 6.907 days, and the majority of these have half-lives that are less than 24 seconds. This element also has 27 meta states, with the most stable being ^156m1Tb, ^154m2Tb and ^154m1Tb.

Naturally occurring europium (₆₃Eu) is composed of two isotopes, ¹⁵¹Eu and ¹⁵³Eu, with ¹⁵³Eu being the most abundant (52.2% natural abundance). While ¹⁵³Eu is observationally stable (theoretically can undergo alpha decay with half-life over 5.5×10¹⁷ years), ¹⁵¹Eu was found in 2007 to be unstable and undergo alpha decay. The half-life is measured to be (4.62 ± 0.95(stat.) ± 0.68(syst.)) × 10¹⁸ years which corresponds to 1 alpha decay per two minutes in every kilogram of natural europium. Besides the natural radioisotope ¹⁵¹Eu, 36 artificial radioisotopes have been characterized, with the most stable being ¹⁵⁰Eu with a half-life of 36.9 years, ¹⁵²Eu with a half-life of 13.516 years, ¹⁵⁴Eu with a half-life of 8.593 years, and ¹⁵⁵Eu with a half-life of 4.7612 years. The majority of the remaining radioactive isotopes, which range from ¹³⁰Eu to ¹⁷⁰Eu, have half-lives that are less than 12.2 seconds. This element also has 18 metastable isomers, with the most stable being ^150mEu (t_1/2 12.8 hours), ^152m1Eu (t_1/2 9.3116 hours) and ^152m5Eu (t_1/2 96 minutes).

Naturally occurring samarium (₆₂Sm) is composed of five stable isotopes, ¹⁴⁴Sm, ¹⁴⁹Sm, ¹⁵⁰Sm, ¹⁵²Sm and ¹⁵⁴Sm, and two extremely long-lived radioisotopes, ¹⁴⁷Sm and ¹⁴⁸Sm, with ¹⁵²Sm being the most abundant. ¹⁴⁶Sm is also fairly long-lived, but is not long-lived enough to have survived in significant quantities from the formation of the Solar System on Earth, although it remains useful in radiometric dating in the Solar System as an extinct radionuclide. It is the longest-lived nuclide that has not yet been confirmed to be primordial.

Naturally occurring neodymium (₆₀Nd) is composed of 5 stable isotopes, ¹⁴²Nd, ¹⁴³Nd, ¹⁴⁵Nd, ¹⁴⁶Nd and ¹⁴⁸Nd, with ¹⁴²Nd being the most abundant (27.2% natural abundance), and 2 long-lived radioisotopes, ¹⁴⁴Nd and ¹⁵⁰Nd. In all, 33 radioisotopes of neodymium have been characterized up to now, with the most stable being naturally occurring isotopes ¹⁴⁴Nd (alpha decay, a half-life (t_1/2) of 2.29×10¹⁵ years) and ¹⁵⁰Nd (double beta decay, t_1/2 of 7×10¹⁸ years), and for practical purposes they can be considered to be stable as well. All of the remaining radioactive isotopes have half-lives that are less than 12 days, and the majority of these have half-lives that are less than 70 seconds; the most stable artificial isotope is ¹⁴⁷Nd with a half-life of 10.98 days. This element also has 13 known meta states with the most stable being ^139mNd (t_1/2 5.5 hours), ^135mNd (t_1/2 5.5 minutes) and ^133m1Nd (t_1/2 ~70 seconds).

Naturally occurring praseodymium (₅₉Pr) 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, ^142mPr and ^134mPr.

Naturally occurring lanthanum (₅₇La) is composed of one stable (¹³⁹La) and one radioactive (¹³⁸La) isotope, with the stable isotope, ¹³⁹La, being the most abundant (99.91% natural abundance). There are 39 radioisotopes that have been characterized, with the most stable being ¹³⁸La, with a half-life of 1.02×10¹¹ years; ¹³⁷La, with a half-life of 60,000 years and ¹⁴⁰La, with a half-life of 1.6781 days. The remaining radioactive isotopes have half-lives that are less than a day and the majority of these have half-lives that are less than 1 minute. This element also has 12 nuclear isomers, the longest-lived of which is ^132mLa, with a half-life of 24.3 minutes. Lighter isotopes mostly decay to isotopes of barium and heavy ones mostly decay to isotopes of cerium. ¹³⁸La can decay to both.

Antimony (₅₁Sb) occurs in two stable isotopes, ¹²¹Sb and ¹²³Sb. There are 37 artificial radioactive isotopes, the longest-lived of which are ¹²⁵Sb, with a half-life of 2.75856 years; ¹²⁴Sb, with a half-life of 60.2 days; and ¹²⁶Sb, with a half-life of 12.35 days. All other isotopes have half-lives less than 4 days, most less than an hour. There are also many isomers, the longest-lived of which is ^120m1Sb with a half-life of 5.76 days.

Tin (₅₀Sn) is the element with the greatest number of stable isotopes. This is probably related to the fact that 50 is a "magic number" of protons. In addition, twenty-nine unstable tin isotopes are known, including tin-100 (¹⁰⁰Sn) and tin-132 (¹³²Sn), which are both "doubly magic". The longest-lived tin radioisotope is tin-126 (¹²⁶Sn), with a half-life of 230,000 years. The other 28 radioisotopes have half-lives of less than a year.

Naturally occurring cadmium (₄₈Cd) is composed of 8 isotopes. For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays have not been observed, due to extremely long half-lives. The two natural radioactive isotopes are ¹¹³Cd (beta decay, half-life is 8.04 × 10¹⁵ years) and ¹¹⁶Cd (two-neutrino double beta decay, half-life is 2.8 × 10¹⁹ years). The other three are ¹⁰⁶Cd, ¹⁰⁸Cd (double electron capture), and ¹¹⁴Cd (double beta decay); only lower limits on their half-life times have been set. Three isotopes—¹¹⁰Cd, ¹¹¹Cd, and ¹¹²Cd—are theoretically stable. Among the isotopes absent in natural cadmium, the most long-lived are ¹⁰⁹Cd with a half-life of 462.6 days, and ¹¹⁵Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours and the majority of these have half-lives that are less than 5 minutes. This element also has 12 known meta states, with the most stable being ^113mCd (t_1/2 14.1 years), ^115mCd (t_1/2 44.6 days) and ^117mCd (t_1/2 3.36 hours).

Naturally occurring rhodium (₄₅Rh) is composed of only one stable isotope, ¹⁰³Rh. The most stable radioisotopes are ¹⁰¹Rh with a half-life of 3.3 years, ¹⁰²Rh with a half-life of 207 days, and ⁹⁹Rh with a half-life of 16.1 days. Thirty other radioisotopes have been characterized with atomic weights ranging from 88.949 u (⁸⁹Rh) to 121.943 u (¹²²Rh). Most of these have half-lives that are less than an hour except ¹⁰⁰Rh and ¹⁰⁵Rh. There are also numerous meta states with the most stable being ^102mRh (0.141 MeV) with a half-life of about 3.7 years and ^101mRh (0.157 MeV) with a half-life of 4.34 days.

Natural yttrium (₃₉Y) is composed of a single isotope yttrium-89. The most stable radioisotopes are ⁸⁸Y, which has a half-life of 106.6 days, and ⁹¹Y, with a half-life of 58.51 days. All the other isotopes have half-lives of less than a day, except ⁸⁷Y, which has a half-life of 79.8 hours, and ⁹⁰Y, with 64 hours. The dominant decay mode below the stable ⁸⁹Y is electron capture and the dominant mode after it is beta emission. Thirty-five unstable isotopes have been characterized.

Rubidium (₃₇Rb) has 36 isotopes, with naturally occurring rubidium being composed of just two isotopes; ⁸⁵Rb (72.2%) and the radioactive ⁸⁷Rb (27.8%).

Arsenic (₃₃As) has 32 known isotopes and at least 10 isomers. Only one of these isotopes, ⁷⁵As, is stable; as such, it is considered a monoisotopic element. The longest-lived radioisotope is ⁷³As with a half-life of 80 days.

Naturally occurring scandium (₂₁Sc) is composed of one stable isotope, ⁴⁵Sc. Twenty-seven radioisotopes have been characterized, with the most stable being ⁴⁶Sc with a half-life of 83.8 days, ⁴⁷Sc with a half-life of 3.35 days, and ⁴⁸Sc with a half-life of 43.7 hours and ⁴⁴Sc with a half-life of 3.97 hours. All the remaining isotopes have half-lives that are less than four hours, and the majority of these have half-lives that are less than two minutes, the least stable being proton unbound ³⁹Sc with a half-life shorter than 300 nanoseconds. This element also has 13 meta states with the most stable being ^44m2Sc.

References

1 2 3 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.
1 2 3 4 5 6 7 8 Kiss, G. G.; Vitéz-Sveiczer, A.; Saito, Y.; et al. (2022). "Measuring the β-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the nucleosynthesis yields in the rare-earth region". The Astrophysical Journal. 936 (107): 107. Bibcode:2022ApJ...936..107K. doi: 10.3847/1538-4357/ac80fc . hdl: 2117/375253 .
↑ Belli, P.; Bernabei, R.; Cappella, F.; et al. (2007). "Search for α decay of natural Europium". Nuclear Physics A. 789 (1–4): 15–29. Bibcode:2007NuPhA.789...15B. doi:10.1016/j.nuclphysa.2007.03.001.
↑ "Apollo Experience Report - Protection Against Radiation" (PDF). NASA. Archived from the original (PDF) on 14 November 2014. Retrieved 9 December 2011.

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.2003.11.001
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.2003.11.001
- 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.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[2] Pm – Excited nuclear isomer.

[3] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-4] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-5] 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[6] Modes of decay:
EC: Electron capture
IT: Isomeric transition
p: Proton emission

[7] Bold italics symbol as daughter – Daughter product is nearly stable.

[8] Bold symbol as daughter – Daughter product is stable.

[9] ( ) spin value – Indicates spin with weak assignment arguments.

[FP-10] 1 2 3 Fission product

[11] Spontaneous fission product of ²³²Th, ²³⁵U, ²³⁸U and alpha decay daughter of primordial ¹⁵¹Eu

[NUBASE2020-1] 1 2 3 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.

[Ln922-12] 1 2 3 4 5 6 7 8 Kiss, G. G.; Vitéz-Sveiczer, A.; Saito, Y.; et al. (2022). "Measuring the β-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the nucleosynthesis yields in the rare-earth region". The Astrophysical Journal. 936 (107): 107. Bibcode:2022ApJ...936..107K. doi: 10.3847/1538-4357/ac80fc . hdl: 2117/375253 .

[13] Belli, P.; Bernabei, R.; Cappella, F.; et al. (2007). "Search for α decay of natural Europium". Nuclear Physics A. 789 (1–4): 15–29. Bibcode:2007NuPhA.789...15B. doi:10.1016/j.nuclphysa.2007.03.001.

[14] "Apollo Experience Report - Protection Against Radiation" (PDF). NASA. Archived from the original (PDF) on 14 November 2014. Retrieved 9 December 2011.

[1]

[n 1]

[n 2]

[n 3]

[n 4]

[n 5]

[n 6]

[n 7]

[n 8]

[n 9]

[n 10]

[2]

[3]

[4]