Francium Francium is a chemical element with the symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain it appears in), has a half-life of only 22&nb ...

(₈₇Fr) has no stable

isotopes Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

. A

standard atomic weight The standard atomic weight of a chemical element (symbol ''A''r°(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, is ...

cannot be given. Its most stable isotope is ²²³Fr with a half-life of 22 minutes, occurring in trace quantities as an intermediate

decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( ...

of ²³⁵U. Of elements whose most stable isotopes have been identified with certainty, francium is the most unstable. All elements with atomic number of 106 ( seaborgium) or greater have most-stable-known isotopes shorter than that of francium, but as those elements have only a relatively small number of isotopes discovered, the possibility remains that undiscovered isotopes of these elements may have longer half-lives.

List of isotopes

, - , ¹⁹⁹Fr , , style="text-align:right" , 87 , style="text-align:right" , 112 , 199.00726(4) , 16(7) ms , , , 1/2+# , , - , ²⁰⁰Fr , , style="text-align:right" , 87 , style="text-align:right" , 113 , 200.00657(8) , 24(10) ms , α , ¹⁹⁶At , 3+# , , - , rowspan=2 style="text-indent:1em" , ^200mFr , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 60(110) keV , rowspan=2, 650(210) ms , α , ¹⁹⁶At , rowspan=2, 10−# , rowspan=2, , - , IT (rare) , ²⁰⁰Fr , - , rowspan=2, ²⁰¹Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 114 , rowspan=2, 201.00386(8) , rowspan=2, 67(3) ms , α (99%) , ¹⁹⁷At , rowspan=2, (9/2−) , rowspan=2, , - , β⁺ (1%) , ²⁰¹Rn , - , rowspan=2, ²⁰²Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 115 , rowspan=2, 202.00337(5) , rowspan=2, 290(30) ms , α (97%) , ¹⁹⁸At , rowspan=2, (3+) , rowspan=2, , - , β⁺ (3%) , ²⁰²Rn , - , rowspan=2 style="text-indent:1em" , ^202mFr , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 330(90)# keV , rowspan=2, 340(40) ms , α (97%) , ¹⁹⁸At , rowspan=2, (10−) , rowspan=2, , - , β⁺ (3%) , ²⁰²Rn , - , rowspan=2, ²⁰³Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 116 , rowspan=2, 203.000925(17) , rowspan=2, 0.55(2) s , α (95%) , ¹⁹⁹At , rowspan=2, (9/2−)# , rowspan=2, , - , β⁺ (5%) , ²⁰³Rn , - , rowspan=2, ²⁰⁴Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 117 , rowspan=2, 204.000653(26) , rowspan=2, 1.7(3) s , α (96%) , ²⁰⁰At , rowspan=2, (3+) , rowspan=2, , - , β⁺ (4%) , ²⁰⁴Rn , - , rowspan=2 style="text-indent:1em" , ^204m1Fr , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 50(4) keV , rowspan=2, 2.6(3) s , α (90%) , ²⁰⁰At , rowspan=2, (7+) , rowspan=2, , - , β⁺ (10%) , ²⁰⁴Rn , - , style="text-indent:1em" , ^204m2Fr , , colspan="3" style="text-indent:2em" , 326(4) keV , 1.7(6) s , , , (10−) , , - , rowspan=2, ²⁰⁵Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 118 , rowspan=2, 204.998594(8) , rowspan=2, 3.80(3) s , α (99%) , ²⁰¹At , rowspan=2, (9/2−) , rowspan=2, , - , β⁺ (1%) , ²⁰⁵Rn , - , rowspan=2, ²⁰⁶Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 119 , rowspan=2, 205.99867(3) , rowspan=2, ~16 s , β⁺ (58%) , ²⁰⁶Rn , rowspan=2, (2+, 3+) , rowspan=2, , - , α (42%) , ²⁰²At , - , style="text-indent:1em" , ^206m1Fr , , colspan="3" style="text-indent:2em" , 190(40) keV , 15.9(1) s , , , (7+) , , - , style="text-indent:1em" , ^206m2Fr , , colspan="3" style="text-indent:2em" , 730(40) keV , 700(100) ms , , , (10−) , , - , rowspan=2, ²⁰⁷Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 120 , rowspan=2, 206.99695(5) , rowspan=2, 14.8(1) s , α (95%) , ²⁰³At , rowspan=2, 9/2− , rowspan=2, , - , β⁺ (5%) , ²⁰⁷Rn , - , rowspan=2, ²⁰⁸Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 121 , rowspan=2, 207.99714(5) , rowspan=2, 59.1(3) s , α (90%) , ²⁰⁴At , rowspan=2, 7+ , rowspan=2, , - , β⁺ (10%) , ²⁰⁸Rn , - , rowspan=2, ²⁰⁹Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 122 , rowspan=2, 208.995954(16) , rowspan=2, 50.0(3) s , α (89%) , ²⁰⁵At , rowspan=2, 9/2− , rowspan=2, , - , β⁺ (11%) , ²⁰⁹Rn , - , rowspan=2, ²¹⁰Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 123 , rowspan=2, 209.996408(24) , rowspan=2, 3.18(6) min , α (60%) , ²⁰⁶At , rowspan=2, 6+ , rowspan=2, , - , β⁺ (40%) , ²¹⁰Rn , - , rowspan=2, ²¹¹Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 124 , rowspan=2, 210.995537(23) , rowspan=2, 3.10(2) min , α (80%) , ²⁰⁷At , rowspan=2, 9/2− , rowspan=2, , - , β⁺ (20%) , ²¹¹Rn , - , rowspan=2, ²¹²Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 125 , rowspan=2, 211.996202(28) , rowspan=2, 20.0(6) min , β⁺ (57%) , ²¹²Rn , rowspan=2, 5+ , rowspan=2, , - , α (43%) , ²⁰⁸At , - , rowspan=2, ²¹³Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 126 , rowspan=2, 212.996189(8) , rowspan=2, 34.6(3) s , α (99.45%) , ²⁰⁹At , rowspan=2, 9/2− , rowspan=2, , - , β⁺ (.55%) , ²¹³Rn , - , ²¹⁴Fr , , style="text-align:right" , 87 , style="text-align:right" , 127 , 213.998971(9) , 5.0(2) ms , α , ²¹⁰At , (1−) , , - , style="text-indent:1em" , ^214m1Fr , , colspan="3" style="text-indent:2em" , 123(6) keV , 3.35(5) ms , α , ²¹⁰At , (8−) , , - , style="text-indent:1em" , ^214m2Fr , , colspan="3" style="text-indent:2em" , 638(6) keV , 103(4) ns , , , (11+) , , - , style="text-indent:1em" , ^214m3Fr , , colspan="3" style="text-indent:2em" , 6477+Y keV , 108(7) ns , , , (33+) , , - , ²¹⁵Fr , , style="text-align:right" , 87 , style="text-align:right" , 128 , 215.000341(8) , 86(5) ns , α , ²¹¹At , 9/2− , , - , rowspan=2, ²¹⁶Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 129 , rowspan=2, 216.003198(15) , rowspan=2, 0.70(2) μs , α , ²¹²At , rowspan=2, (1−) , rowspan=2, , - , β⁺ (2×10⁻⁷%) , ²¹⁶Rn , - , ²¹⁷Fr , , style="text-align:right" , 87 , style="text-align:right" , 130 , 217.004632(7) , 16.8(19) μs , α , ²¹³At , 9/2− , , - , ²¹⁸Fr , , style="text-align:right" , 87 , style="text-align:right" , 131 , 218.007578(5) , 1.0(6) ms , α , ²¹⁴At , 1− , , - , rowspan=2 style="text-indent:1em" , ^218m1Fr , rowspan=2, , rowspan=2 colspan="3" style="text-indent:2em" , 86(4) keV , rowspan=2, 22.0(5) ms , α , ²¹⁴At , rowspan=2, , rowspan=2, , - , IT (rare) , ²¹⁸Fr , - , style="text-indent:1em" , ^218m2Fr , , colspan="3" style="text-indent:2em" , 200(150)# keV , , , , high , , - , ²¹⁹Fr , , style="text-align:right" , 87 , style="text-align:right" , 132 , 219.009252(8) , 20(2) ms , α , ²¹⁵At , 9/2− , , - , rowspan=2, ²²⁰Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 133 , rowspan=2, 220.012327(4) , rowspan=2, 27.4(3) s , α (99.65%) , ²¹⁶At , rowspan=2, 1+ , rowspan=2, , - , β⁻ (.35%) , ²²⁰Ra , - , rowspan=3, ²²¹Fr , rowspan=3, , rowspan=3 style="text-align:right" , 87 , rowspan=3 style="text-align:right" , 134 , rowspan=3, 221.014255(5) , rowspan=3, 4.9(2) min , α (99.9%) , ²¹⁷At , rowspan=3, 5/2− , rowspan=3, TraceIntermediate decay product of ²³⁷Np , - , β⁻ (.1%) , ²²¹Ra , - , CD (8.79×10⁻¹¹%) , ²⁰⁷Tl
¹⁴C , - , ²²²Fr , , style="text-align:right" , 87 , style="text-align:right" , 135 , 222.017552(23) , 14.2(3) min , β⁻ , ²²²Ra , 2− , , - , rowspan=2, ²²³Fr , rowspan=2, Actinium K , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 136 , rowspan=2, 223.0197359(26) , rowspan=2, 22.00(7) min , β⁻ (99.99%) , ²²³Ra , rowspan=2, 3/2(−) , rowspan=2, TraceIntermediate

of ²³⁵U , - , α (.006%) , ²¹⁹At , - , ²²⁴Fr , , style="text-align:right" , 87 , style="text-align:right" , 137 , 224.02325(5) , 3.33(10) min , β⁻ , ²²⁴Ra , 1− , , - , ²²⁵Fr , , style="text-align:right" , 87 , style="text-align:right" , 138 , 225.02557(3) , 4.0(2) min , β⁻ , ²²⁵Ra , 3/2− , , - , ²²⁶Fr , , style="text-align:right" , 87 , style="text-align:right" , 139 , 226.02939(11) , 49(1) s , β⁻ , ²²⁶Ra , 1− , , - , ²²⁷Fr , , style="text-align:right" , 87 , style="text-align:right" , 140 , 227.03184(11) , 2.47(3) min , β⁻ , ²²⁷Ra , 1/2+ , , - , ²²⁸Fr , , style="text-align:right" , 87 , style="text-align:right" , 141 , 228.03573(22)# , 38(1) s , β⁻ , ²²⁸Ra , 2− , , - , ²²⁹Fr , , style="text-align:right" , 87 , style="text-align:right" , 142 , 229.03845(4) , 50.2(4) s , β⁻ , ²²⁹Ra , (1/2+)# , , - , ²³⁰Fr , , style="text-align:right" , 87 , style="text-align:right" , 143 , 230.04251(48)# , 19.1(5) s , β⁻ , ²³⁰Ra , , , - , ²³¹Fr , , style="text-align:right" , 87 , style="text-align:right" , 144 , 231.04544(50)# , 17.6(6) s , β⁻ , ²³¹Ra , (1/2+)# , , - , ²³²Fr , , style="text-align:right" , 87 , style="text-align:right" , 145 , 232.04977(69)# , 5(1) s , β⁻ , ²³²Ra , ,

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes