Protactinium, with the chemical symbol Pa and atomic number 91, is a fascinating and rare chemical element discovered in 1913. German scientists Otto Hahn and Lise Meitner made the discovery when bombarding uranium with neutrons, leading to the identification of the short-lived isotope Protactinium-234. The name "Protactinium" is derived from the Greek word "protos," meaning "the first," reflecting its position in the decay process of uranium-235.
Protactinium exists on Earth in trace amounts, primarily as a decay product of uranium. Due to its rarity and radioactive nature, it has limited applications. It was previously used in nuclear reactors as a neutron source. The key Protactinium isotopes are Protactinium-231 and Protactinium-233. Protactinium-231 has a half-life of about 32,760 years, while Protactinium-233 has a half-life of approximately 27 days.