Actinium is a radioactive chemical element with the symbol Ac and atomic number 89. It is a silvery-white, rare and radioactive metal that is found in uranium ores. Actinium is a member of the actinide series and is the first element in the series
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 identified with a substance André-Louis Debierne found in 1899 and called 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.