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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. [2]
Nuclide [n 1] | Historic name | Z | N | Isotopic mass (Da) [n 2] [n 3] | Half-life | Decay mode | Daughter isotope [n 4] [n 5] | Spin and parity [n 6] [n 7] | Isotopic abundance | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Excitation energy [n 7] | |||||||||||||||||||
186Po | 84 | 102 | 186.004403(20) | 28+16 −6 μs | α | 182Pb | 0+ | ||||||||||||
187Po | 84 | 103 | 187.003030(40) | 1.40(25) ms | α | 183Pb | 1/2−, 5/2− | ||||||||||||
187mPo | 4(27) keV | 0.5 ms | α | 183Pb | 13/2+# | ||||||||||||||
188Po | 84 | 104 | 187.999416(21) | 270(30) μs | α | 184Pb | 0+ | ||||||||||||
189Po | 84 | 105 | 188.998473(24) | 3.5(5) ms | α | 185Pb | (5/2−) | ||||||||||||
190Po | 84 | 106 | 189.995102(14) | 2.45(5) ms | α | 186Pb | 0+ | ||||||||||||
191Po | 84 | 107 | 190.994558(8) | 22(1) ms | α | 187Pb | 3/2− | ||||||||||||
191mPo | 61(11) keV | 93(3) ms | α | 187mPb | 13/2+ | ||||||||||||||
192Po | 84 | 108 | 191.991340(11) | 32.2(3) ms | α | 188Pb | 0+ | ||||||||||||
192mPo | 2294.6(10) keV | 580(100) ns | IT | 192Po | 11− | ||||||||||||||
193Po | 84 | 109 | 192.991062(16) | 399(34) ms | α | 189Pb | 3/2− | ||||||||||||
193mPo | 100(6) keV | 245(11) ms | α | 189mPb | 13/2+ | ||||||||||||||
194Po | 84 | 110 | 193.988186(14) | 392(4) ms | α | 190Pb | 0+ | ||||||||||||
194mPo | 2313.4(3) keV | 12.9(5) μs | IT | 194Po | (10−) | ||||||||||||||
195Po | 84 | 111 | 194.988066(6) | 4.64(9) s | α (94%) | 191Pb | 3/2− | ||||||||||||
β+? | 195Bi | ||||||||||||||||||
195mPo | 148(9) keV | 1.92(2) s | α | 191mPb | 13/2+ | ||||||||||||||
196Po | 84 | 112 | 195.985541(6) | 5.56(12) s | α (94%) | 192Pb | 0+ | ||||||||||||
β+? | 196Bi | ||||||||||||||||||
196mPo | 2493.9(4) keV | 856(17) ns | IT | 196Po | 11− | ||||||||||||||
197Po | 84 | 113 | 196.985622(11) | 53.6(9) s | β+? | 197Bi | (3/2−) | ||||||||||||
α (44%) | 193Pb | ||||||||||||||||||
197mPo | 196(12)# keV | 25.8(1) s | α (84%) | 193mPb | 13/2+ | ||||||||||||||
β+? | 197Bi | ||||||||||||||||||
IT? | 197Po | ||||||||||||||||||
198Po | 84 | 114 | 197.983389(19) | 1.760(24) min | α (57%) | 194Pb | 0+ | ||||||||||||
β+ (43%) | 198Bi | ||||||||||||||||||
198m1Po | 2565.92(20) keV | 200(20) ns | IT | 198Po | 11− | ||||||||||||||
198m2Po | 2740(50)# keV | 750(50) ns | IT | 198Po | 12+ | ||||||||||||||
199Po | 84 | 115 | 198.983666(25) | 5.48(16) min | β+ (92.5%) | 199Bi | (3/2−) | ||||||||||||
α (7.5%) | 195Pb | ||||||||||||||||||
199mPo | 312.0(28) keV | 4.17(4) min | β+ (73.5%) | 199Bi | 13/2+ | ||||||||||||||
α (24%) | 195Pb | ||||||||||||||||||
IT (2.5%) | 199Po | ||||||||||||||||||
200Po | 84 | 116 | 199.981799(15) | 11.5(1) min | β+ (88.8%) | 200Bi | 0+ | ||||||||||||
α (11.1%) | 196Pb | ||||||||||||||||||
201Po | 84 | 117 | 200.982260(6) | 15.3(2) min | β+ (98.4%) | 201Bi | 3/2− | ||||||||||||
α (1.6%) | 197Pb | ||||||||||||||||||
201mPo | 424.1(24) keV | 8.9(2) min | IT (56.2(12)%) | 201Po | 13/2+ | ||||||||||||||
β+ (41.4(7)%) | 201Bi | ||||||||||||||||||
α (2.4(5)%) | 197Pb | ||||||||||||||||||
202Po | 84 | 118 | 201.980758(16) | 44.7(5) min | β+ (98%) | 202Bi | 0+ | ||||||||||||
α (2%) | 198Pb | ||||||||||||||||||
202mPo | 2626.7(7) keV | >200 ns | 11− | ||||||||||||||||
203Po | 84 | 119 | 202.981420(28) | 36.7(5) min | β+ (99.89%) | 203Bi | 5/2− | ||||||||||||
α (.11%) | 199Pb | ||||||||||||||||||
203m1Po | 641.49(17) keV | 45(2) s | IT (99.96%) | 203Po | 13/2+ | ||||||||||||||
α (.04%) | 199Pb | ||||||||||||||||||
203m2Po | 2158.5(6) keV | >200 ns | |||||||||||||||||
204Po | 84 | 120 | 203.980318(12) | 3.53(2) h | β+ (99.33%) | 204Bi | 0+ | ||||||||||||
α (.66%) | 200Pb | ||||||||||||||||||
205Po | 84 | 121 | 204.981203(21) | 1.66(2) h | β+ (99.96%) | 205Bi | 5/2− | ||||||||||||
α (.04%) | 201Pb | ||||||||||||||||||
205m1Po | 143.166(17) keV | 310(60) ns | 1/2− | ||||||||||||||||
205m2Po | 880.30(4) keV | 645 μs | 13/2+ | ||||||||||||||||
205m3Po | 1461.21(21) keV | 57.4(9) ms | IT | 205Po | 19/2− | ||||||||||||||
205m4Po | 3087.2(4) keV | 115(10) ns | 29/2− | ||||||||||||||||
206Po | 84 | 122 | 205.980481(9) | 8.8(1) d | β+ (94.55%) | 206Bi | 0+ | ||||||||||||
α (5.45%) | 202Pb | ||||||||||||||||||
206m1Po | 1585.85(11) keV | 222(10) ns | (8+)# | ||||||||||||||||
206m2Po | 2262.22(14) keV | 1.05(6) μs | (9−)# | ||||||||||||||||
207Po | 84 | 123 | 206.981593(7) | 5.80(2) h | β+ (99.97%) | 207Bi | 5/2− | ||||||||||||
α (.021%) | 203Pb | ||||||||||||||||||
207m1Po | 68.573(14) keV | 205(10) ns | 1/2− | ||||||||||||||||
207m2Po | 1115.073(16) keV | 49(4) μs | 13/2+ | ||||||||||||||||
207m3Po | 1383.15(6) keV | 2.79(8) s | IT | 207Po | 19/2− | ||||||||||||||
208Po | 84 | 124 | 207.9812457(19) | 2.898(2) y | α (99.99%) | 204Pb | 0+ | ||||||||||||
β+ (.00277%) | 208Bi | ||||||||||||||||||
209Po | 84 | 125 | 208.9824304(20) | 124(3) y | α (99.546%) | 205Pb | 1/2− | ||||||||||||
β+ (.454%) | 209Bi | ||||||||||||||||||
210Po [n 8] | Radium F | 84 | 126 | 209.9828737(13) | 138.376(2) d | α | 206Pb | 0+ | Trace [n 9] | ||||||||||
210mPo | 5057.61(4) keV | 263(5) ns | 16+ | ||||||||||||||||
211Po | Actinium C' | 84 | 127 | 210.9866532(14) | 516(3) ms | α | 207Pb | 9/2+ | Trace [n 10] | ||||||||||
211m1Po | 1462(5) keV | 25.2(6) s | α (99.98%) | 207Pb | (25/2+) | ||||||||||||||
IT (.016%) | 211Po | ||||||||||||||||||
211m2Po | 2135.7(9) keV | 243(21) ns | (31/2−) | ||||||||||||||||
211m3Po | 4873.3(17) keV | 2.8(7) μs | (43/2+) | ||||||||||||||||
212Po | Thorium C' | 84 | 128 | 211.9888680(13) | 294.4(8) ns [1] | α | 208Pb | 0+ | Trace [n 11] | ||||||||||
212mPo | 2911(12) keV | 45.1(6) s | α (99.93%) | 208Pb | (18+) | ||||||||||||||
IT (.07%) [3] [4] | 212Po | ||||||||||||||||||
213Po | 84 | 129 | 212.992857(3) | 3.65(4) μs | α | 209Pb | 9/2+ | Trace [n 12] | |||||||||||
214Po | Radium C' | 84 | 130 | 213.9952014(16) | 164.3(20) μs | α | 210Pb | 0+ | Trace [n 9] | ||||||||||
215Po | Actinium A | 84 | 131 | 214.9994200(27) | 1.781(4) ms | α (99.99%) | 211Pb | 9/2+ | Trace [n 10] | ||||||||||
β− (2.3×10−4%) | 215At | ||||||||||||||||||
216Po | Thorium A | 84 | 132 | 216.0019150(24) | 145(2) ms | α [n 13] | 212Pb | 0+ | Trace [n 11] | ||||||||||
217Po | 84 | 133 | 217.006335(7) | 1.47(5) s | α (95%) | 213Pb | 5/2+# | Trace [n 12] | |||||||||||
β− (5%) | 217At | ||||||||||||||||||
218Po | Radium A | 84 | 134 | 218.0089730(26) | 3.10(1) min | α (99.98%) | 214Pb | 0+ | Trace [n 9] | ||||||||||
β− (.02%) | 218At | ||||||||||||||||||
219Po | 84 | 135 | 219.01361(16) | 10.3(1) min | α (28.2%) | 215Pb | 9/2+# | ||||||||||||
β− (71.8%) | 219At | ||||||||||||||||||
220Po | 84 | 136 | 220.0164(18) | 40# s [>300 ns] | β− | 220At | 0+ | ||||||||||||
221Po | 84 | 137 | 221.02123(20) | 2.2(0.7) min | β− | 221At | 9/2+# | ||||||||||||
222Po | 84 | 138 | 222.024144(40) | 9.1(7.2) min | β− | 222At | 0+ | ||||||||||||
223Po | 84 | 139 | 223.02907(21)# | 6# s [>300 ns] | β−? | 223At | 11/2+# | ||||||||||||
224Po | 84 | 140 | 224.03211(21)# | 3# min [>300 ns] | β−? | 224At | 0+ | ||||||||||||
225Po | 84 | 141 | 225.03712(32)# | 10# s [>300 ns] | β−? | 225At | 3/2+# | ||||||||||||
226Po | 84 | 142 | 226.04031(43)# | 1# min [>300 ns] | β−? | 226At | 0+ | ||||||||||||
227Po | 84 | 143 | 227.04539(43)# | 2# s [>300 ns] | β−? | 227At | 5/2+# | ||||||||||||
This table header & footer: |
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. Radium has 34 known isotopes from 201Ra to 234Ra.
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.
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.
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 platinum (78Pt) consists of five stable isotopes (192Pt, 194Pt, 195Pt, 196Pt, 198Pt) and one very long-lived (half-life 4.83×1011 years) radioisotope (190Pt). There are also 34 known synthetic radioisotopes, the longest-lived of which is 193Pt with a half-life of 50 years. All other isotopes have half-lives under a year, most under a day. All isotopes of platinum are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed. Platinum-195 is the most abundant isotope.
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 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 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.
Naturally occurring barium (56Ba) is a mix of six stable isotopes and one very long-lived radioactive primordial isotope, barium-130, identified as being unstable by geochemical means (from analysis of the presence of its daughter xenon-130 in rocks) in 2001. This nuclide decays by double electron capture (absorbing two electrons and emitting two neutrinos), with a half-life of (0.5–2.7)×1021 years (about 1011 times the age of the universe).
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 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.
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 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 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.
Berkelium (97Bk) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 243Bk in 1949. There are twenty known radioisotopes, from 233Bk and 233Bk to 253Bk, and six nuclear isomers. The longest-lived isotope is 247Bk with a half-life of 1,380 years.
Einsteinium (99Es) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be discovered was 253Es in 1952. There are 18 known radioisotopes from 240Es to 257Es, and 4 nuclear isomers. The longest-lived isotope is 252Es with a half-life of 471.7 days, or around 1.293 years.
Mendelevium (101Md) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 256Md in 1955. There are 17 known radioisotopes, ranging in atomic mass from 244Md to 260Md, and 5 isomers. The longest-lived isotope is 258Md with a half-life of 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 57 minutes.
Isotope data is sourced in: