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Radium
Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, which has a half-life of 1601 years and decays into radon gas...
Timeline of Events
1898
12.26.1898
Marie and Pierre Curie announce the isolation of radium.
1902
4.20.1902
Pierre and Marie Curie refine radium chloride.
1936
2.4.1936
Radium becomes the first radioactive element to be made synthetically.