Lanthanum

Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the first and the prototype of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table. Lanthanum is traditionally counted among the rare-earth elements. Like most other rare-earth elements, its usual oxidation state is +3, although some compounds are known with an oxidation state of +2. Lanthanum has no biological role in humans but is used by some bacteria. It is not par

Swedish chemist and mineralogist (1797–1858)

series of tests during and after the Manhattan Project designed to study the behavior of converging shock waves to achieve the spherical implosion necessary for compression of the plutonium pit of the nuclear weapon