Actinium
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Actinium is a chemical element; it has symbol Ac and atomic number 89. It was discovered by Friedrich Oskar Giesel in 1902, who gave it the name emanium; the element got its name by being wrongly iden
Uraninite ores have elevated concentrations of actinium.
Radium
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Radium is a chemical element; it has symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, bu
Actinium
…The actinide series, a set of 15 elements between actinium and lawrencium in the periodic table, is named after actinium. Together with polonium, radium, and radon, actinium was one of the first non-primordial radioactive elements to be discovered. A soft, silvery-white radioactive metal, actinium reacts…
Radium electroplated on a very small sample of copper foil and covered with polyurethane to prevent reaction with the air
Radium-226 radiation source. Activity 3300 Bq (3.3 kBq)
Marie and Pierre Curie experimenting with radium, a drawing by André Castaigne
Glass tube of radium chloride kept by the US Bureau of Standards that served as the primary standard of radioactivity for the United States in 1927.