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Standard atomic weight Ar°(Ce) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Naturally occurring cerium (58Ce) is composed of 4 stable isotopes: 136Ce, 138Ce, 140Ce, and 142Ce, with 140Ce being the most abundant (88.48% natural abundance) and the only one theoretically stable; 136Ce, 138Ce, and 142Ce are predicted to undergo double beta decay but this process has never been observed. There are 35 radioisotopes that have been characterized, with the most stable being 144Ce, with a half-life of 284.893 days; 139Ce, with a half-life of 137.640 days and 141Ce, with a half-life of 32.501 days. All of the remaining radioactive isotopes have half-lives that are less than 4 days and the majority of these have half-lives that are less than 10 minutes. This element also has 10 meta states.
The isotopes of cerium range in atomic weight from 119 u (119Ce) to 157 u (157Ce).
Nuclide [n 1] | Z | N | Isotopic mass (Da) [n 2] [n 3] | Half-life [n 4] | Decay mode [n 5] | Daughter isotope [n 6] | Spin and parity [n 7] [n 4] | Natural abundance (mole fraction) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Excitation energy | Normal proportion | Range of variation | |||||||||||||||||
119Ce | 58 | 61 | 118.95276(64)# | 200# ms | β+ | 119La | 5/2+# | ||||||||||||
120Ce | 58 | 62 | 119.94664(75)# | 250# ms | β+ | 120La | 0+ | ||||||||||||
121Ce | 58 | 63 | 120.94342(54)# | 1.1(1) s | β+ | 121La | (5/2)(+#) | ||||||||||||
122Ce | 58 | 64 | 121.93791(43)# | 2# s | β+ | 122La | 0+ | ||||||||||||
β+, p | 121Ba | ||||||||||||||||||
123Ce | 58 | 65 | 122.93540(32)# | 3.8(2) s | β+ | 123La | (5/2)(+#) | ||||||||||||
β+, p | 122Ba | ||||||||||||||||||
124Ce | 58 | 66 | 123.93041(32)# | 9.1(12) s | β+ | 124La | 0+ | ||||||||||||
125Ce | 58 | 67 | 124.92844(21)# | 9.3(3) s | β+ | 125La | (7/2−) | ||||||||||||
β+, p | 124Ba | ||||||||||||||||||
126Ce | 58 | 68 | 125.92397(3) | 51.0(3) s | β+ | 126La | 0+ | ||||||||||||
127Ce | 58 | 69 | 126.92273(6) | 29(2) s | β+ | 127La | 5/2+# | ||||||||||||
128Ce | 58 | 70 | 127.91891(3) | 3.93(2) min | β+ | 128La | 0+ | ||||||||||||
129Ce | 58 | 71 | 128.91810(3) | 3.5(3) min | β+ | 129La | (5/2+) | ||||||||||||
130Ce | 58 | 72 | 129.91474(3) | 22.9(5) min | β+ | 130La | 0+ | ||||||||||||
130mCe | 2453.6(3) keV | 100(8) ns | (7−) | ||||||||||||||||
131Ce | 58 | 73 | 130.91442(4) | 10.2(3) min | β+ | 131La | (7/2+) | ||||||||||||
131mCe | 61.8(1) keV | 5.0(10) min | β+ | 131La | (1/2+) | ||||||||||||||
132Ce | 58 | 74 | 131.911460(22) | 3.51(11) h | β+ | 132La | 0+ | ||||||||||||
132mCe | 2340.8(5) keV | 9.4(3) ms | IT | 132Ce | (8−) | ||||||||||||||
133Ce | 58 | 75 | 132.911515(18) | 97(4) min | β+ | 133La | 1/2+ | ||||||||||||
133mCe | 37.1(8) keV | 4.9(4) d | β+ | 133La | 9/2− | ||||||||||||||
134Ce | 58 | 76 | 133.908925(22) | 3.16(4) d | EC | 134La | 0+ | ||||||||||||
135Ce | 58 | 77 | 134.909151(12) | 17.7(3) h | β+ | 135La | 1/2(+) | ||||||||||||
135mCe | 445.8(2) keV | 20(1) s | IT | 135Ce | (11/2−) | ||||||||||||||
136Ce | 58 | 78 | 135.907172(14) | Observationally Stable [n 8] | 0+ | 0.00185(2) | 0.00185–0.00186 | ||||||||||||
136mCe | 3095.5(4) keV | 2.2(2) μs | 10+ | ||||||||||||||||
137Ce | 58 | 79 | 136.907806(14) | 9.0(3) h | β+ | 137La | 3/2+ | ||||||||||||
137mCe | 254.29(5) keV | 34.4(3) h | IT (99.22%) | 137Ce | 11/2− | ||||||||||||||
β+ (.779%) | 137La | ||||||||||||||||||
138Ce | 58 | 80 | 137.905991(11) | Observationally Stable [n 9] | 0+ | 0.00251(2) | 0.00251–0.00254 | ||||||||||||
138mCe | 2129.17(12) keV | 8.65(20) ms | IT | 138Ce | 7- | ||||||||||||||
139Ce | 58 | 81 | 138.906653(8) | 137.641(20) d | EC | 139La | 3/2+ | ||||||||||||
139mCe | 754.24(8) keV | 56.54(13) s | IT | 139Ce | 11/2− | ||||||||||||||
140Ce [n 10] | 58 | 82 | 139.9054387(26) | Stable | 0+ | 0.88450(51) | 0.88446–0.88449 | ||||||||||||
140mCe | 2107.85(3) keV | 7.3(15) μs | 6+ | ||||||||||||||||
141Ce [n 10] | 58 | 83 | 140.9082763(26) | 32.508(13) d | β− | 141Pr | 7/2− | ||||||||||||
142Ce [n 10] | 58 | 84 | 141.909244(3) | Observationally Stable [n 11] [4] [5] | 0+ | 0.11114(51) | 0.11114–0.11114 | ||||||||||||
143Ce [n 10] | 58 | 85 | 142.912386(3) | 33.039(6) h | β− | 143Pr | 3/2− | ||||||||||||
144Ce [n 10] | 58 | 86 | 143.913647(4) | 284.91(5) d | β− | 144mPr | 0+ | ||||||||||||
145Ce | 58 | 87 | 144.91723(4) | 3.01(6) min | β− | 145Pr | (3/2−) | ||||||||||||
146Ce | 58 | 88 | 145.91876(7) | 13.52(13) min | β− | 146Pr | 0+ | ||||||||||||
147Ce | 58 | 89 | 146.92267(3) | 56.4(10) s | β− | 147Pr | (5/2−) | ||||||||||||
148Ce | 58 | 90 | 147.92443(3) | 56(1) s | β− | 148Pr | 0+ | ||||||||||||
149Ce | 58 | 91 | 148.9284(1) | 5.3(2) s | β− | 149Pr | (3/2−)# | ||||||||||||
150Ce | 58 | 92 | 149.93041(5) | 4.0(6) s | β− | 150Pr | 0+ | ||||||||||||
151Ce | 58 | 93 | 150.93398(11) | 1.02(6) s | β− | 151Pr | 3/2−# | ||||||||||||
152Ce | 58 | 94 | 151.93654(21)# | 1.4(2) s | β− | 152Pr | 0+ | ||||||||||||
153Ce | 58 | 95 | 152.94058(43)# | 500# ms [>300 ns] | β− | 153Pr | 3/2−# | ||||||||||||
154Ce | 58 | 96 | 153.94342(54)# | 300# ms [>300 ns] | β− | 154Pr | 0+ | ||||||||||||
155Ce | 58 | 97 | 154.94804(64)# | 200# ms [>300 ns] | β− | 155Pr | 5/2−# | ||||||||||||
156Ce | 58 | 98 | 155.95126(64)# | 150# ms | β− | 156Pr | 0+ | ||||||||||||
157Ce | 58 | 99 | 156.95634(75)# | 50# ms | β− | 157Pr | 7/2+# | ||||||||||||
This table header & footer: |
EC: | Electron capture |
IT: | Isomeric transition |
p: | Proton emission |
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, 222Rn, 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.
Naturally occurring tungsten (74W) consists of five isotopes. Four are considered stable (182W, 183W, 184W, and 186W) and one is slightly radioactive, 180W, with an extremely long half-life of 1.8 ± 0.2 exayears (1018 years). On average, two alpha decays of 180W occur per gram of natural tungsten per year, so for most practical purposes, 180W can be considered stable. Theoretically, all five can decay into isotopes of element 72 (hafnium) by alpha emission, but only 180W has been observed to do so. The other naturally occurring isotopes have not been observed to decay (they are observationally stable), and lower bounds for their half-lives have been established:
Natural hafnium (72Hf) consists of five observationally stable isotopes (176Hf, 177Hf, 178Hf, 179Hf, and 180Hf) and one very long-lived radioisotope, 174Hf, with a half-life of 7.0×1016 years. In addition, there are 34 known synthetic radioisotopes, the most stable of which is 182Hf with a half-life of 8.9×106 years. This extinct radionuclide is used in hafnium–tungsten dating to study the chronology of planetary differentiation.
Naturally occurring thulium (69Tm) is composed of one stable isotope, 169Tm. Thirty-nine radioisotopes have been characterized, with the most stable being 171Tm with a half-life of 1.92 years, 170Tm with a half-life of 128.6 days, 168Tm with a half-life of 93.1 days, and 167Tm with a half-life of 9.25 days. All of the remaining radioactive isotopes have half-lives that are less than 64 hours, and the majority of these have half-lives that are less than 2 minutes. This element also has 26 meta states, with the most stable being 164mTm, 160mTm and 155mTm.
Natural holmium (67Ho) contains one observationally stable isotope, 165Ho. The below table lists 36 isotopes spanning 140Ho through 175Ho as well as 33 nuclear isomers. Among the known synthetic radioactive isotopes; the most stable one is 163Ho, with a half-life of 4,570 years. All other radioisotopes have half-lives not greater than 1.117 days in their ground states, and most have half-lives under 3 hours.
Naturally occurring dysprosium (66Dy) is composed of 7 stable isotopes, 156Dy, 158Dy, 160Dy, 161Dy, 162Dy, 163Dy and 164Dy, with 164Dy being the most abundant. Twenty-nine radioisotopes have been characterized, with the most stable being 154Dy with a half-life of 1.4 million years, 159Dy with a half-life of 144.4 days, and 166Dy with a half-life of 81.6 hours. All of the remaining radioactive isotopes have half-lives that are less than 10 hours, and the majority of these have half-lives that are less than 30 seconds. This element also has 12 meta states, with the most stable being 165mDy, 147mDy and 145mDy.
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 gadolinium (64Gd) is composed of 6 stable isotopes, 154Gd, 155Gd, 156Gd, 157Gd, 158Gd and 160Gd, and 1 radioisotope, 152Gd, with 158Gd being the most abundant (24.84% natural abundance). The predicted double beta decay of 160Gd has never been observed; only a lower limit on its half-life of more than 1.3×1021 years has been set experimentally.
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 (t1/2 12.8 hours), 152m1Eu (t1/2 9.3116 hours) and 152m5Eu (t1/2 96 minutes).
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.
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 (t1/2 14.1 years), 115mCd (t1/2 44.6 days) and 117mCd (t1/2 3.36 hours).
Naturally occurring ruthenium (44Ru) is composed of seven stable isotopes. Additionally, 27 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are 106Ru, with a half-life of 373.59 days; 103Ru, with a half-life of 39.26 days and 97Ru, with a half-life of 2.9 days.
Naturally occurring zinc (30Zn) is composed of the 5 stable isotopes 64Zn, 66Zn, 67Zn, 68Zn, and 70Zn with 64Zn being the most abundant. Twenty-eight radioisotopes have been characterised with the most stable being 65Zn with a half-life of 244.26 days, and then 72Zn with a half-life of 46.5 hours. All of the remaining radioactive isotopes have half-lives that are less than 14 hours and the majority of these have half-lives that are less than 1 second. This element also has 10 meta states.
Copper (29Cu) has two stable isotopes, 63Cu and 65Cu, along with 28 radioisotopes. The most stable radioisotope is 67Cu with a half-life of 61.83 hours. Most of the others have half-lives under a minute. Unstable copper isotopes with atomic masses below 63 tend to undergo β+ decay, while isotopes with atomic masses above 65 tend to undergo β− decay. 64Cu decays by both β+ and β−.
Naturally occurring manganese (25Mn) is composed of one stable isotope, 55Mn. Twenty-seven radioisotopes have been characterized, with the most stable being 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.3 days, and 52Mn with a half-life of 5.591 days. All of the remaining radioactive isotopes have half-lives that are less than 3 hours and the majority of these have half-lives that are less than a minute. This element also has seven meta states.
Naturally occurring chromium (24Cr) is composed of four stable isotopes; 50Cr, 52Cr, 53Cr, and 54Cr with 52Cr being the most abundant (83.789% natural abundance). 50Cr is suspected of decaying by β+β+ to 50Ti with a half-life of (more than) 1.8×1017 years. Twenty-two radioisotopes, all of which are entirely synthetic, have been characterized, the most stable being 51Cr with a half-life of 27.7 days. All of the remaining radioactive isotopes have half-lives that are less than 24 hours and the majority of these have half-lives that are less than 1 minute. This element also has two meta states, 45mCr, the more stable one, and 59mCr, the least stable isotope or isomer.
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.