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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]
The CsFr molecule is predicted to have francium at the negative end of the dipole, unlike all known heterodiatomic alkali metal molecules. Francium superoxide (FrO 2) is expected to have a more covalent character than its lighter congeners; this is attributed to the 6p electrons in francium being more involved in the francium–oxygen bonding. [4]
The most reactive metals, such as sodium, will react with cold water to produce hydrogen and the metal hydroxide: 2 Na (s) + 2 H 2 O (l) →2 NaOH (aq) + H 2 (g) Metals in the middle of the reactivity series, such as iron , will react with acids such as sulfuric acid (but not water at normal temperatures) to give hydrogen and a metal salt ...
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 ...
However, it would appear that francium perchlorate has been formed, as it coprecipitates with caesium perchlorate, and several other insoluble francium salts are similarly known (Hyde, E.K., Radiochemical Methods for the Isolation of Element 87 (Francium), J. Am. Chem. Soc., 1952, 74, 4181) The article also quotes a value for the Pauling ...
Why is francium so unstable? The article doesn't explain. Google found me a Prezi presentation (), but first off that's not a reliable source for expanding the francium article, and secondly it doesn't explain why many isotopes of related elements, e.g. 238 U with 54 more neutrons than protons, are so much longer lived.
The direct reaction of hydrocarbons with fluorine gas can be dangerously reactive, so the temperature may need to be lowered even to −150 °C (−240 °F). [115] " Solid fluorine carriers", compounds that can release fluorine upon heating, notably cobalt trifluoride , [ 116 ] may be used instead, or hydrogen fluoride.
Water-reactive substances [1] are those that spontaneously undergo a chemical reaction with water, often noted as generating flammable gas. [2] Some are highly reducing in nature. [ 3 ] Notable examples include alkali metals , lithium through caesium , and alkaline earth metals , magnesium through barium .