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Lawrencium (Lr) is a synthetic element with atomic number 103 and atomic weight 262. It was discovered in 1961 at the Lawrence Radiation Laboratory and named after Ernest O. Lawrence. Lawrencium is the last of the actinides and was first produced by bombarding californium with boron ions. Its short half-life and limited production make it difficult to study. Twelve isotopes have been synthesized, with Lawrencium-266 having the longest half-life of 11 hours. Some isotopes have been observed to be produced by the decay of heavier elements.
Lawrentium is an element with atomic symbol Lr, atomic number 103, and atomic weight 262. It was discovered at the Lawrence Radiation Laboratory – now the Lawrence Livermore National Laboratory – on the University of California at Berkeley campus by Albert Ghiorso, Almon E. Larsh, Robert M. Latimer and Torbjørn Sikkeland on Valentine’s Day 1961. Named after Ernest O. Lawrence, who invented the cyclotron. Originally designated to be represented by the atomic symbol Lw, the symbol was later changed to Lr.
Lawrencium is the last of the actinides or transuranic actinoids, as well as the last of the group to be discovered, ending a 173-year process. It all started when natural uranium was discovered by Martin Heinrich Klaproth, a German chemist, in 1789. But the development of this area is delayed somewhat until a wave of discoveries of transuranic actinoids, all discovered synthetically , began with neptunium in 1940.
Lawrentium was first produced by bombarding californium with boron ions. The small amounts of lawrencium that have been created so far, combined with the very short half-life of lawrentium, make it difficult to process and describe. Its color, for example, is a matter of conjecture, as is its melting point.
The first isolate had a half-life of 8 seconds. Twelve isotopes have been synthesized so far: Lawrencium (Lawrencium-252, -254, -255, -256, -257, -258, -259, -260, -261, -262 and -266), together with a nuclear isomer, -253. The isotope with the longest half-life discovered to date is Lawrencium-266, with a reported half-life of 11 hours. Lawrencium-262 was first discovered in 2014.
Some isotopes of Lawrencium have been observed to be produced by the decay of heavier elements, such as bohrium, dubnium, meitnerium and ununtrium.
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