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 metallurgy to any appreciable extent that is fissile, that is, fissionable by thermal neutrons. The isotope U is also important because it absorbs neutrons to produce a radioactive isotope that subsequently decays to the isotope 239Pu (plutonium), which also is fissile. Uranium in its natural state comprises just 0.71% U and 99.3% U, and the main focus of uranium metallurgy is the enrichment of uranium through isotope separation. Uranium metallurgy In materials science and materials engineering, uranium metallurgy is the study of the physical and chemical behavior of uranium and its alloys. Commercial-grade uranium can be produced through the reduction of