Actinium (Ac, atomic number 89) is a radioactive element discovered in 1899. It was the first such element not found in nature to be isolated. Radon and radium and their distinctive properties were noted before those of actinium, but these elements were isolated in 1902. The actinide series (15 elements that are of similar type) is named after actinium.
Actinium was discovered by Andre-Louis Debierne, a French chemist. He extracted it from the residues left by Marie and Pierre Curie following their discovery of radium. In 1902, Friedrich Oskar Giesel discovered actinium independently. He described it as an element similar...Read More