Element 93 is known as neptunium, a radioactive metal that was first discovered in 1940. It is part of the actinide series on the periodic table and is primarily produced through the irradiation of uranium in nuclear reactors. Neptunium has no significant commercial applications but is used in research and as a precursor for the production of plutonium. Neptunium is characterized by its silvery appearance and is highly reactive, especially with oxygen and moisture. It has several isotopes, with neptunium-237 being the most stable and having a half-life of about 2.14 million years. Due to its radioactivity, neptunium must be handled with care in controlled environments.