Radium


In 26th December 1948, Pierre and Marie Curie announced the discovery of this element. It had been distinguished from polonium due to the likeliness of its chemical properties with those of barium. Its sulfate and carbonate were insoluble and the chloride was soluble in water but insoluble in hydrochloride acid or in alcohol. However, this element was not identical to barium, and could easily be separated.