Actinium is a rare earth metal that is part of the actinide series in the periodic table. It is highly radioactive and has various isotopes, the most stable of which is Actinium-227 with a half-life of 21.77 years. It is found in small quantities in uranium and thorium ores and is isolated through the use of ion exchange techniques. Actinium has various applications in nuclear science and medicine. Its isotopes can emit alpha, beta, and gamma radiation, and have been used as a neutron source in nuclear reactors. Actinium-225, one of its isotopes, holds promise in targeted alpha therapy for cancer treatment. It selectively targets cancer cells and delivers a lethal dose of radiation to them while sparing the surrounding healthy tissue.