| Isotopes of Francium | 
|  Notes | 
| Francium-223 is the most stable isotope with a half-llife of 21.8 minutes, and it is highly unlikely that an isotope of francium with a longer half-llife will ever be discovered or synthesized. | 
|  Notable Isotopes  | 
|  221Fr [134 neutrons] | 
|  Abundance: synthetic | 
|  Half life: 4.8 minutes [ Alpha Decay ] | 
|  Decay Energy: 6.457 MeV | 
|  Decays to 217At. | 
|  222Fr [135 neutrons] | 
|  Abundance: synthetic | 
|  Half life: 14.2 minutes [ beta- ] | 
|  Decay Energy: 2.033 MeV | 
|  Decays to 222Ra. | 
|  223Fr [136 neutrons] | 
|  Abundance: 100% | 
|  Half life: 22.00 minutes [ beta- ] | 
|  Decay Energy: 1.149 MeV | 
|  Decays to 221Ra. | 
|  Half life: 22.00 minutes [ Alpha Decay ] | 
|  Decay Energy: 5.430 MeV | 
|  Decays to 219At. |