Uranium is a chemical element with the symbol U and atomic number 92. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, who named the new element after the recently discovered planet Uranus. Eugène-Melchior Péligot was the first person to isolate the metal, and its radioactive properties were discovered in 1896 by Henri Becquerel. Research by Otto Hahn, Lise Meitner, Enrico Fermi, and others, such as J. Robert Oppenheimer, starting in 1934, led to its use as a fuel in the nuclear power industry and Little Boy, the first nuclear weapon used in war.

Actinide Chemical Elements

The actinide series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.

These fifteen actinide elements [Actinium (Ac), Thorium (Th), Protactinium (Pa), Uranium (U), Neptunium (Np), Plutonium (Pu), Americium (Am), Curium (Cm), Berkelium (Bk), Californium (Cf), Einsteinium (Es), Fermium (Fm), Mendelevium (Md), Nobelium (No), Lawrencium (Lr)], have very large atomic and ionic radii and exhibit an unusually large range of physical properties.