Period 7 element elements of the 7th period. Francium is a chemical element with symbol Fr and atomic number 87. It was formerly known as eka-caesium and actinium K. It is one of the two least electronegative elements, the other being caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon. 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. It was the last element discovered in nature, rather than by synthesis. Outside the laboratory, francium is extremely rare, with trace amounts
Uranium nitride and, in particular, it undergoes an (n,p) reaction which produces significant amounts of radioactive C which would need to be carefully contained and sequestered during reprocessing or permanent storage. Each uranium dinitride complex is considered to have three distinct compounds present simultaneously because of decomposing of uranium dinitride (UN) into uranium sesquinitride (UN), and the uranium mononitride (UN). Uranium dinitrides decompose to uranium mononitride by the following sequence of reactions: Decomposition of UN is the most common method for isolating uranium sesquinitride (UN). Uranium mononitride is being considered as a potential fuel for generation IV reactors such as the Hyperion