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 trioxide which operates at the world's largest uranium refinery at Blind River, Ontario, produces high-purity uranium trioxide. It has been reported that the corrosion of uranium in a silica rich aqueous solution forms uranium dioxide, uranium trioxide, and coffinite. In pure water, schoepite (UO)O(OH)·12(HO) is formed in the first week and then after four months studtite (UO)O·4(HO) was produced. This alteration of uranium oxide also leads to the formation of metastudtite, Like all hexavalent uranium compounds, UO is hazardous by inhalation, ingestion, and through skin contact. It is a poisonous, slightly radioactive substance, which may cause shortness of breath, coughing, acute