lawrencium

lawrencium artificially produced radioactive chemical element; symbol Lr; at. no. 103; mass number of most stable isotope 262; m.p. about 1,627°C; b.p. and sp. gr. unknown; valence +3. Lawrencium is the last member of the actinide series of elements found in Group 3 of the periodic table . Lawrencium was the 11th transuranium element to be discovered. It was first prepared in 1961 (after three years of preliminary work) by Albert Ghiorso, Torbjørn Sikkeland, Almon E. Larsh, and Robert M. Latimer at the Univ. of California at Berkeley; a sample of californium isotopes was bombarded with a beam of boron nuclei from the heavy-ion linear accelerator. The resulting isotope, lawrencium-258, had a half-life of 4.2 sec. The element was named for Ernest O. Lawrence , the inventor of the cyclotron. The symbol Lw was used at first, but it was changed to Lr in 1963. Ten isotopes, all of which are radioactive, are known; the most stable, lawrencium-262, has a half-life of 3.6 hours.

law·ren·ci·um / lôˈrensēəm/ • n. the chemical element of atomic number 103, a radioactive metal of the actinide series. Lawrencium does not occur naturally and was first made by bombarding californium with boron nuclei. (Symbol: Lr)

lawrencium (symbol Lr) Radioactive metallic element, one of the actinide series. It was first made in 1961 at the University of California at Berkeley by bombarding californium with boron nuclei. It is named after the US physicist Ernest Lawrence who established the laboratory where it was produced. Properties: at.no. 103; r.a.m. 262; most stable isotope Lr²⁵⁶ (half-life 27 seconds).