Lawrencium
Lawrencium was first synthesized by the nuclear-physics team led by Albert Ghiorso on February 14, 1961, at the Lawrence Berkeley National Laboratory of the University of California. The first atoms of lawrencium were produced by bombarding a three-milligram target consisting of three isotopes of the element californium with boron-10 and boron-11 nuclei from the Heavy Ion Linear Accelerator. The team suggested the name lawrencium (after Ernest Lawrence), and the symbol "Lw", but IUPAC changed the symbol to "Lr" in 1963. It was the last element of the actinide series to be produced.
All isotopes of lawrencium are radioactive; its most stable known isotope is lawrencium-262, with a half-life of approximately 3.6 hours. All its isotopes except for lawrencium-260, -261 and -262 decay with a half-life of less than a minute.
Discovery of Lawrencium
Lawrencium was synthesized in 1961 by Albert Ghiorso, Torbjørn Sikkeland, Almon Larsh and Robert Latimer at the Lawrence Berkeley National Laboratory, California. It was the last member of the actinide series to be discovered.
A heavy-ion linear accelerator (HILAC) was used to bombard a 3 milligram target of californium (consisting of a mixture of californium isotopes of mass number 249, 250, 251, and 252) with boron-10 and boron-11 ions, producing lawrencium.
The target consisted of a mixture of californium isotopes and therefore an exact mass of the new element could not be assigned. Later research suggested that lawrencium-258 (half-life 4.2 seconds) was produced in the 1961 experiment.
The element was named after Ernest Lawrence, inventor of the cyclotron particle accelerator.
The symbol Lw was used originally, but in 1963 this was changed by The International Union of Pure and Applied Chemistry (IUPAC) to Lr.
| Symbol | Lr | |
| Atomic Number | 103 | |
| Atomic Weight | 262.11 | |
| Oxidation States | +3 | |
| Electronegativity, Pauling | ||
| State at RT | Solid, Metal | |
| Melting Point, K | ||
| Boiling Point, K |
Appearance and Characteristics
Harmful effects:
Lawrencium is harmful due to its radioactivity.
Characteristics:
- Lawrencium is a synthetic, highly radioactive metal that has only been produced in miniscule amounts.
- Lawrencium is a trivalent ion in aqueous solution.
- Lawrencium metal has not been prepared.
- All of its isotopes are short-lived. Its longest lived isotopes is 262Lr with a half-life of 216 minutes.
Uses of Lawrencium
- Lawrencium is of scientific research interest only.
