Actinium, with the chemical symbol Ac and atomic number 89, is a captivating chemical element discovered in 1899. Friedrich Oskar Giesel, a German chemist, first identified it in uranium ore, and later confirmed the discovery with Friedrich Oskar Hahn. The name "Actinium" derives from the Greek word "aktinos," meaning "ray" or "beam," reflecting the element's radioactive properties.
Actinium is extremely rare on Earth and does not occur naturally. It is produced as a decay product of uranium and thorium. Although it has limited applications due to its rarity and radioactive nature, it has been used in the past in medical radiation sources. The key Actinium isotopes are Actinium-227 and Actinium-228. Actinium-227 has a half-life of about 21.8 years, while Actinium-228 has a half-life of approximately 6.15 hours.