Francium Francium is a chemical element; it has 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 in which it appears), has a half-l ...

(₈₇Fr) has no stable

isotopes Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They 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), but ...

, thus 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, ...

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 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 ( d ...

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 Seaborgium is a synthetic chemical element; it has symbol Sg and atomic number 106. It is named after the American nuclear chemist Glenn T. Seaborg. As a synthetic element, it can be created in a laboratory but is not found in nature. It is als ...

) 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

, -id=Francium-197 , ¹⁹⁷Fr , , style="text-align:right" , 87 , style="text-align:right" , 110 , 197.01101(6) , 2.3(19) ms , α , ¹⁹³At , (7/2−) , , -id=Francium-198 , ¹⁹⁸Fr , , style="text-align:right" , 87 , style="text-align:right" , 111 , 198.01028(3) , 15(3) ms , α , ¹⁹⁴At , 3+# , , -id=Francium-199 , ¹⁹⁹Fr , , style="text-align:right" , 87 , style="text-align:right" , 112 , 199.007269(15) , 16(7) ms , α , ¹⁹⁵At , 1/2+# , , -id=Francium-200 , ²⁰⁰Fr , , style="text-align:right" , 87 , style="text-align:right" , 113 , 200.00658(3) , 24(10) ms , α , ¹⁹⁶At , 3+# , , -id=Francium-200m , style="text-indent:1em" , ^200mFr , , colspan="3" style="text-indent:2em" , 60(110) keV , 190(120) ms , α , ¹⁹⁶At , 10−# , , -id=Francium-201 , rowspan=2, ²⁰¹Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 114 , rowspan=2, 201.003852(10) , rowspan=2, 67(3) ms , α (99%) , ¹⁹⁷At , rowspan=2, (9/2−) , rowspan=2, , - , β⁺ (1%) , ²⁰¹Rn , -id=Francium-202 , rowspan=2, ²⁰²Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 115 , rowspan=2, 202.003330(6) , rowspan=2, 290(30) ms , α (97%) , ¹⁹⁸At , rowspan=2, (3+) , rowspan=2, , - , β⁺ (3%) , ²⁰²Rn , -id=Francium-202m , 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 , -id=Francium-203 , rowspan=2, ²⁰³Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 116 , rowspan=2, 203.000941(7) , rowspan=2, 0.55(2) s , α (95%) , ¹⁹⁹At , rowspan=2, (9/2−)# , rowspan=2, , - , β⁺ (5%) , ²⁰³Rn , -id=Francium-204 , rowspan=2, ²⁰⁴Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 117 , rowspan=2, 204.000652(26) , rowspan=2, 1.7(3) s , α (96%) , ²⁰⁰At , rowspan=2, (3+) , rowspan=2, , - , β⁺ (4%) , ²⁰⁴Rn , -id=Francium-204m1 , 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 , -id=Francium-204m2 , style="text-indent:1em" , ^204m2Fr , , colspan="3" style="text-indent:2em" , 326(4) keV , 1.7(6) s , , , (10−) , , -id=Francium-205 , 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 , -id=Francium-206 , rowspan=2, ²⁰⁶Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 119 , rowspan=2, 205.998661(30) , rowspan=2, ~16 s , β⁺ (58%) , ²⁰⁶Rn , rowspan=2, (2+, 3+) , rowspan=2, , - , α (42%) , ²⁰²At , -id=Francium-206m1 , style="text-indent:1em" , ^206m1Fr , , colspan="3" style="text-indent:2em" , 190(40) keV , 15.9(1) s , , , (7+) , , -id=Francium-206m2 , style="text-indent:1em" , ^206m2Fr , , colspan="3" style="text-indent:2em" , 730(40) keV , 700(100) ms , , , (10−) , , -id=Francium-207 , rowspan=2, ²⁰⁷Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 120 , rowspan=2, 206.996941(19) , rowspan=2, 14.8(1) s , α (95%) , ²⁰³At , rowspan=2, 9/2− , rowspan=2, , - , β⁺ (5%) , ²⁰⁷Rn , -id=Francium-208 , rowspan=2, ²⁰⁸Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 121 , rowspan=2, 207.997139(13) , rowspan=2, 59.1(3) s , α (90%) , ²⁰⁴At , rowspan=2, 7+ , rowspan=2, , - , β⁺ (10%) , ²⁰⁸Rn , -id=Francium-209 , rowspan=2, ²⁰⁹Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 122 , rowspan=2, 208.995940(12) , rowspan=2, 50.0(3) s , α (89%) , ²⁰⁵At , rowspan=2, 9/2− , rowspan=2, , - , β⁺ (11%) , ²⁰⁹Rn , -id=Francium-210 , rowspan=2, ²¹⁰Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 123 , rowspan=2, 209.996411(14) , rowspan=2, 3.18(6) min , α (60%) , ²⁰⁶At , rowspan=2, 6+ , rowspan=2, , - , β⁺ (40%) , ²¹⁰Rn , -id=Francium-211 , rowspan=2, ²¹¹Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 124 , rowspan=2, 210.995555(13) , rowspan=2, 3.10(2) min , α (80%) , ²⁰⁷At , rowspan=2, 9/2− , rowspan=2, , - , β⁺ (20%) , ²¹¹Rn , -id=Francium-212 , rowspan=2, ²¹²Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 125 , rowspan=2, 211.996225(9) , rowspan=2, 20.0(6) min , β⁺ (57%) , ²¹²Rn , rowspan=2, 5+ , rowspan=2, , - , α (43%) , ²⁰⁸At , -id=Francium-213 , rowspan=2, ²¹³Fr , rowspan=2, , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 126 , rowspan=2, 212.996184(5) , rowspan=2, 34.14(6) s , α (99.45%) , ²⁰⁹At , rowspan=2, 9/2− , rowspan=2, , - , β⁺ (.55%) , ²¹³Rn , -id=Francium-214 , ²¹⁴Fr , , style="text-align:right" , 87 , style="text-align:right" , 127 , 213.998971(9) , 5.0(2) ms , α , ²¹⁰At , (1−) , , -id=Francium-214m1 , style="text-indent:1em" , ^214m1Fr , , colspan="3" style="text-indent:2em" , 123(6) keV , 3.35(5) ms , α , ²¹⁰At , (8−) , , -id=Francium-214m2 , style="text-indent:1em" , ^214m2Fr , , colspan="3" style="text-indent:2em" , 638(6) keV , 103(4) ns , , , (11+) , , -id=Francium-214m3 , style="text-indent:1em" , ^214m3Fr , , colspan="3" style="text-indent:2em" , 6477+Y keV , 108(7) ns , , , (33+) , , -id=Francium-215 , ²¹⁵Fr , , style="text-align:right" , 87 , style="text-align:right" , 128 , 215.000342(8) , 86(5) ns , α , ²¹¹At , 9/2− , , -id=Francium-216 , ²¹⁶Fr , , style="text-align:right" , 87 , style="text-align:right" , 129 , 216.003190(4) , 0.70(2) μs , α , ²¹²At , (1−) , , -id=Francium-216m , style="text-indent:1em" , ^216mFr , , colspan="3" style="text-indent:2em" , 219(6) keV , 850(30) ns , α , ^212m1At , (9−) , , -id=Francium-217 , ²¹⁷Fr , , style="text-align:right" , 87 , style="text-align:right" , 130 , 217.004632(7) , 16.8(19) μs , α , ²¹³At , 9/2− , , -id=Francium-218 , ²¹⁸Fr , , style="text-align:right" , 87 , style="text-align:right" , 131 , 218.007579(5) , 1.0(6) ms , α , ²¹⁴At , 1− , , -id=Francium-218m1 , style="text-indent:1em" , ^218m1Fr , , colspan="3" style="text-indent:2em" , 86(4) keV , 22.0(5) ms , α , ²¹⁴At , (8−) , , -id=Francium-218m2 , style="text-indent:1em" , ^218m2Fr , , colspan="3" style="text-indent:2em" , 200(150)# keV , , , , high , , -id=Francium-219 , ²¹⁹Fr , , style="text-align:right" , 87 , style="text-align:right" , 132 , 219.009251(7) , 20(2) ms , α , ²¹⁵At , 9/2− , , -id=Francium-220 , 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 , -id=Francium-221 , rowspan=3, ²²¹Fr , rowspan=3, , rowspan=3 style="text-align:right" , 87 , rowspan=3 style="text-align:right" , 134 , rowspan=3, 221.014254(5) , rowspan=3, 4.801(5) min , α (99.9%) , ²¹⁷At , rowspan=3, 5/2− , rowspan=3, TraceIntermediate decay product of ²³⁷Np , - , β⁻ (.1%) , ²²¹Ra , - , CD (8.79×10⁻¹¹%)The nuclide with the lowest

atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (''n''p) or the number of pro ...

known to undergo

cluster decay Cluster decay, also named heavy particle radioactivity, heavy ion radioactivity or heavy cluster decay," is a rare type of nuclear decay in which an atomic nucleus emits a small "cluster" of neutrons and protons, more than in an alpha particle, ...

, ²⁰⁷Tl
¹⁴C , -id=Francium-222 , ²²²Fr , , style="text-align:right" , 87 , style="text-align:right" , 135 , 222.017583(8) , 14.2(3) min , β⁻ , ²²²Ra , 2− , , -id=Francium-223 , rowspan=2, ²²³Fr , rowspan=2, Actinium K , rowspan=2 style="text-align:right" , 87 , rowspan=2 style="text-align:right" , 136 , rowspan=2, 223.0197342(21) , rowspan=2, 22.00(7) min , β⁻ (99.99%) , ²²³Ra , rowspan=2, 3/2(−) , rowspan=2, TraceIntermediate

of ²³⁵U , - , α (.006%) , ²¹⁹At , -id=Francium-224 , ²²⁴Fr , , style="text-align:right" , 87 , style="text-align:right" , 137 , 224.023348(12) , 3.33(10) min , β⁻ , ²²⁴Ra , 1− , , -id=Francium-225 , ²²⁵Fr , , style="text-align:right" , 87 , style="text-align:right" , 138 , 225.025572(13) , 4.0(2) min , β⁻ , ²²⁵Ra , 3/2− , , -id=Francium-226 , ²²⁶Fr , , style="text-align:right" , 87 , style="text-align:right" , 139 , 226.029545(7) , 49(1) s , β⁻ , ²²⁶Ra , 1− , , -id=Francium-227 , ²²⁷Fr , , style="text-align:right" , 87 , style="text-align:right" , 140 , 227.031865(6) , 2.47(3) min , β⁻ , ²²⁷Ra , 1/2+ , , -id=Francium-228 , ²²⁸Fr , , style="text-align:right" , 87 , style="text-align:right" , 141 , 228.035839(7) , 38(1) s , β⁻ , ²²⁸Ra , 2− , , -id=Francium-229 , ²²⁹Fr , , style="text-align:right" , 87 , style="text-align:right" , 142 , 229.038291(5) , 50.2(4) s , β⁻ , ²²⁹Ra , (1/2+)# , , -id=Francium-230 , ²³⁰Fr , , style="text-align:right" , 87 , style="text-align:right" , 143 , 230.042391(7) , 19.1(5) s , β⁻ , ²³⁰Ra , , , -id=Francium-231 , ²³¹Fr , , style="text-align:right" , 87 , style="text-align:right" , 144 , 231.045175(8) , 17.6(6) s , β⁻ , ²³¹Ra , (1/2+)# , , -id=Francium-232 , ²³²Fr , , style="text-align:right" , 87 , style="text-align:right" , 145 , 232.049461(15) , 5(1) s , β⁻ , ²³²Ra , , , -id=Francium-233 , ²³³Fr , , style="text-align:right" , 87 , style="text-align:right" , 146 , 233.052518(21) , 900(100) ms , β⁻ , ²³³Ra , 1/2+ # ,

References

* Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes