RaSO4

Radium sulfate, RaSO4, is an inorganic salt consisting of the radium(II) cation and the sulfate anion. It forms a white, crystalline solid that is highly insoluble in water. As a compound of radium, RaSO4 is radioactive and undergoes alpha decay.

Solubility and structure: RaSO4 crystallizes in a lattice related to the sulfate structures seen in other alkaline earth sulfates. It is extremely insoluble in water, with solubility far lower than many other radium compounds, and tends to persist as a precipitate when Ra2+ and SO4^2- are present together. The compound is chemically stable under ordinary conditions but can slowly dissolve in strong acids, releasing radium ions.

Occurrence and production: Radium occurs in trace amounts in uranium- and thorium-bearing ores. RaSO4 can be formed by precipitating radium ions from solution with sulfate ions: Ra2+ + SO4^2- → RaSO4(s). Naturally occurring RaSO4 is rare due to the scarcity and radioactivity of radium, but it has historically been observed in radium-rich minerals as a precipitated phase.

Applications and history: In the early 20th century, radium sulfate was used in radioluminescent materials and as a source of radium for research. Because of serious health risks associated with radium exposure, the use of RaSO4 and other radium compounds has declined and is subject to stringent regulatory controls. Today RaSO4 is primarily of historical and safety interest rather than practical use.

Safety: RaSO4 contains radium-226, with a half-life of about 1600 years, emitting alpha particles. Handling requires specialized containment, shielding, and regulatory compliance to minimize radiological exposure and environmental release.