February 14, 1961 - Lawrencium is discovered
Lawrentium or laurentium is a radioactive synthetic element of the periodic table of elements whose symbol is Lr (formerly Lw) and its atomic number is 103. In the periodic table, it is located in the d block and in period 7, and is the last and heaviest element in the actinide series. Chemical experiments confirmed that lawrencium behaves homologously to lutetium and is chemically similar to other actinides.
Lawrencium was first synthesized on February 14, 1961, by the nuclear physics team at the Lawrence Berkeley National Laboratory of the University of California, led by Albert Ghiorso. The first lawrencium atoms were produced by bombarding a three-milligram target, composed of three isotopes of californium with nuclei of boron-10 and boron-11, from a heavy-ion linear accelerator. The team suggested the element name lawrencium, after American physicist Ernest O. Lawrence (inventor of the cyclortron), and the symbol "Lw", but the IUPAC changed the symbol to "Lr" in 1963.
All isotopes of lawrencium are radioactive; its most stable known isotope is 266Lr, with a half-life of approximately 11 hours, and the other isotopes, except 260Lr,261Lr, and 262Lr, decay with lives of less than one minute.
