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Francium-223 is the most stable isotope, with a half-life of 21.8 minutes, [8] and it is highly unlikely that an isotope of francium with a longer half-life will ever be discovered or synthesized. [22] Francium-223 is a fifth product of the uranium-235 decay series as a daughter isotope of actinium-227; thorium-227 is the more common daughter. [23]
francium-219: 20 meitnerium-275: 20 boron-12: 20.2 radon-197m: 21 rutherfordium-260: 21 astatine-193m1: 21 californium-238: 21.1 beryllium-12: 21.49 francium-218m1: 22.0 tennessine-293: 22 polonium-191: 22 francium-200: 24 nitrogen-22: 24 actinium-206: 25 uranium-217: 26 actinium-220: 26.36 thorium-216: 26.8 meitnerium-268: 27 astatine-193m2 ...
Francium (87 Fr) has no stable isotopes, thus a standard atomic weight cannot be given. Its most stable isotope is 223 Fr with a half-life of 22 minutes, occurring in trace quantities in nature as an intermediate decay product of 235 U. Of elements whose most stable isotopes have been identified with certainty, francium is the most unstable.
Francium (Fr, atomic number 87) is a highly radioactive metal that decays into astatine, radium, or radon. It is one of the two least electronegative elements; the other is caesium. As an alkali metal, it has one valence electron. Francium was discovered by Marguerite Perey in France (from which the element takes its name) in 1939. [8]
However, it is possible that some isotopes that are now considered stable will be revealed to decay with extremely long half-lives (as with 209 Bi). This list depicts what is agreed upon by the consensus of the scientific community as of 2023. [1] For each of the 80 stable elements, the number of the stable isotopes is given.
As a result, element 173 is expected to behave chemically like an alkali metal, and one that might be far more reactive than even caesium (francium and element 119 being less reactive than caesium due to relativistic effects): [90] [19] the calculated ionisation energy for element 173 is 3.070 eV, [91] compared to the experimentally known 3.894 ...
Perey named the element francium, after her home country, and it joined the other alkali metals in Group 1 of the periodic table of elements. [3] [7] Francium is the second rarest element (after astatine) — only about 550g exists in the entire Earth's crust at any given time — and it was the last element to be discovered in nature.
Despite these unsuccessful attempts to observe long-lived superheavy nuclei, [34] new superheavy elements were synthesized every few years in laboratories through light-ion bombardment and cold fusion [k] reactions; rutherfordium, the first transactinide, was discovered in 1969, and copernicium, eight protons closer to the island of stability ...