Radium is a chemical element with symbol Raand atomic number 88. It is the sixth element in the Group 2 of the periodic table. Pure radium is silvery-white in color, but it combines with nitrogen readily on exposure to air and forms a black surface layer of Ra nitride. It was discovered by Marie Sklodowska Curie and Perre Curie in 1898, in the form of radium chloride. They extracted the radium compound from uraninite. It is found in uranium ores at 1 part per 3 million parts uranium.
In nature, It is found in uranium and thorium ores in trace amounts as small as a seventh of a gram per ton of uraninite. It is not necessary for living organisms, and adverse health effects are likely when it is incorporated into biochemical processes because of its radioactivity and chemical reactivity. Currently, other than its use in nuclear medicine, Ra has no commercial applications; formerly, it was used as a radioactive source for radioluminescent devices and also in radioactive quackery for its supposed curative powers. Today, these former applications are no longer in vogue because radium’s toxicity has become known, and less dangerous isotopes are used instead in radioluminescent devices.
Properties of Radium
- It is like barium, is a highly reactive metal and always exhibits its group oxidation state of +2. It forms the colorless Ra2+ cation in aqueous solution, which is highly basic and does not form complexes readily.
- Most radium compounds are therefore simple ionic compounds, though participation from the 6s and 6p electrons is expected due to relativistic effects and would enhance the covalent character of radium compounds such as RaF2 and RaAt2.
- The values for barium and radium are almost exactly the same as those of the heavier alkali metals potassium, rubidium, and caesium.
- Ra is the heaviest known alkaline earth metal and is the only radioactive member of its group. Its physical and chemical properties most closely resemble its lighter congener barium.
- It is a highly reactive metal and always exhibits its group oxidation state. It forms the colorless Ra2+ cation in aqueous solution, which is highly basic and doesn’t form complexes.