It is impractical for use in radiotherapy, because its half-life is to short as for it to be readily transported. Like other Alkali Metals, it has a single valence electron.īecause of its instability, Francium has no applications. The heaviest of the known Alkali Metals, Francium is produced only in atomic quantities for research. This energy hence was coming from another element - this would be Francium. A 7s electron spends very little time near the nucleus, so its increasing bond strength and decreasing orbital radius are noticiable but not dramatic.ĭiscovered in 1939 by French chemist Margeurite Perey, Francium was discovered in a pure sample of Actinium, which had higher energy than thought. In order to do that, the electron must have so much kinetic energy that it becomes more massive - causing its orbital to shrink. Often hailed as the most reactive Alkali Metal, it is thought perhaps it may be less reactive than Caesium, as Francium's lone 7s electron spends a part of its time close to the nucleus. While no macroscopic sample can be obtained without high-order magic, a sample of some 200000 atoms (5E-16 micromole) emitted enough light to allow it to be photographed (see picture). Within about 0.005 sec, the sphere will turn into a tiny nuclear fireball at a temperature approaching 2000 K. A bit of playing with numbers reveals that a 1 mm diameter sphere of 223Fr puts out an average of 245 watts during its first half-life, most of which remains inside the specimen. 223Fr decays by beta emission, releasing 1.15 MeV worth of energy in the process. Atomic radius Ionic radius (1+ ion) 194 pm : Ionic radius (2+ ion). The only isotope of Fr occurring naturally in significant amounts is 223Fr, a descendant of 235U. Franciums properties, interesting facts, discovery, videos, images, states. Its appearance and practical chemistry can be confidently predicted. It is thought that it melts easily compared to its kin of Caesium and Rubidium, and may have a density of ~2.48 g/cm 3. The name of the element comes from English France, the country of its discovery. Perhaps one of only a few true images of Francium - this false-colour image displays the light given off by ~200,000 atoms of it caught in a light trap.įrancium is the chemical element with the chemical symbol Fr, and atomic number 87.
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