Properties
Radium chloride is a colorless-white solid with a blue-green luminescence, especially when heated. Its color gradually changes to yellow with aging, whereas contamination by barium may impart a rose tint. It is less soluble in water than other alkaline earth metal chlorides – at 25 °C its solubility is 245 g/L whereas that of barium chloride is 307 g/L, and the difference is even larger in hydrochloric acid solutions. This property is used in the first stages of the separation of radium from barium by fractional crystallization. Radium chloride is only sparingly soluble in azeotropic hydrochloric acid and virtually insoluble in concentrated hydrochloric acid.
Gaseous radium chloride exists as RaCl2 molecules, as with other alkaline earth metal halides. The gas shows strong absorptions in the visible spectrum at 676.3 nm and 649.8 nm (red): the dissociation energy of the radium–chlorine bond is estimated as 2.9 eV, and its length as 292 pm.
Contrary to diamagnetic barium chloride, radium chloride is weakly paramagnetic with a magnetic susceptibility of 1.05×106. It also differs from barium chloride by the flame color, which is red as opposed to green for barium chloride.
Read more about this topic: Radium Chloride
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