Lawrencium - chemistry.

Lawrencium - chemistry. Lawrencium, symbol Lr, artificially created radioactive metallic element with an atomic number of 103. Lawrencium is one of the transuranium elements of the periodic table (see Periodic Law). Named in honor of the American physicist Ernest Lawrence, it was discovered in 1961 at the Lawrence Berkeley National Laboratory of the University of California by American chemist Albert Ghiorso and his colleagues. A mixture of californium isotopes was bombarded with boron ions to produce short-lived lawrencium isotopes. Ten isotopes are now known. The most stable, with a half-life of about 3 minutes, has a mass number of 260. Only small amounts of lawrencium have been produced. See also Radioactivity. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.