Search results
Results from the WOW.Com Content Network
Francium-223 and francium-221 are the only isotopes that occur in nature, with the former being far more common. [ 21 ] 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 ]
Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table. The valence electrons (here 3s 2 3p 3) are written explicitly for all atoms. Electron configurations of elements beyond hassium (element 108) have never been measured; predictions are used below.
Configurations of elements 109 and above are not available. Predictions from reliable sources have been used for these elements. Grayed out electron numbers indicate subshells filled to their maximum. Bracketed noble gas symbols on the left represent inner configurations that are the same in each period. Written out, these are: He, 2, helium : 1s 2
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]
The electron of the hydrogen-like ununennium atom—oxidized so it has only one electron, Uue 118+ —is predicted to move so quickly that its mass is 1.99 times that of a non-moving electron, a consequence of relativistic effects. For comparison, the figure for hydrogen-like francium is 1.29 and the figure for hydrogen-like caesium is 1.091. [82]
For example, the electron configuration of the neon atom is 1s 2 2s 2 2p 6, meaning that the 1s, 2s, and 2p subshells are occupied by two, two, and six electrons, respectively. Electronic configurations describe each electron as moving independently in an orbital, in an average field created by the nuclei and all the other
This is especially problematic for francium, which by relativistic calculations can be shown to be less electronegative than caesium, but for which the only value (0.7) in the literature predates these calculations.
The collapse of the 5g orbital itself is delayed until around element 125; the electron configurations of the 119-electron isoelectronic series are expected to be [Og]8s 1 for elements 119 through 122, [Og]6f 1 for elements 123 and 124, and [Og]5g 1 for element 125 onwards. [84]