|Boiling Point: unknown
Melting Point: 1900oK, 1626oC, 2961oF
Electron Energy Level.: 2, 8, 18, 32, 32, 9, 2
Isotopes: 16 + None Stable + 1 meta state
Heat of Vaporization: unknown
Heat of Fusion: unknown
Specific Heat: unknown
Atomic Radius: unknown
Ionic Radius: 88pm
|1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10f14 6s2p6d17s2|
Lawrencium was discovered by Albert Ghiorso, Torbjorn Sikkeland, Almon Larsh and Robert M. Latimer on February 14, 1961 at the Berkeley Radiation Laboratory (now called Lawrence Berkeley National Laboratory) on the University of California, Berkeley campus. It was produced by bombarding a 3 milligram target composed of three isotopes of californium with boron-10 and B-11 ions in the Heavy Ion Linear Accelerator (HILAC).
The transmutation nuclei became electrically charged, recoiled with a helium atmosphere and were collected on a thin copper conveyor tape. This tape was then moved in order to place the collected atoms in front of a series of solid-state detectors. The Berkeley team reported that the isotope 257Lr was detected in this manner and decayed by emitting an 8.6 MeV alpha particle with a half-life of of 4.2 seconds.
In 1965, the Dubna workers found a longer-lived lawrencium isotope, 256Lr, with a half-life of 35 seconds.
In 1967, Flerov and associates at the Dubna Laboratory, Russia, reported that they were not able to confirm an alpha emitter with a half-life of 4.2 seconds as 257103. This assignment has been changed to 258Lr or 259Lr.
In 1968, Ghiorso and associates at Berkeley used a few atoms of this isotope to study the oxidation behavior of lawrencium. Using solvent extraction techniques and working very rapidly, they extracted lawrencium ions from a buffered aqueous solution into an organic solvent -- completing each extraction in about 30 seconds. It was found that lawrencium behaves differently from dipositive nobelium and more like the tripositive elements earlier in the actinide series.
Ernest O. Lawrence
The origin of the name, preferred by the American Chemical Society, is in reference to Ernest O. Lawrence, inventor of the cyclotron. The symbol Lw was originally used but in 1963 it was changed to Lr. In August 1997 the International Union of Pure and Applied Chemistry (IUPAC) ratified the name lawrencium and symbol Lr during a meeting in Geneva. Unniltrium (Unt) was sometimes used as a temporary. systematic element name until that time.
Eleven isotopes of element 103 have been synthesized with 262Lr being the longest lived with a half-life of 216 minutes (it decays into 256No. The isotopes of lawrencium decay via alpha emission, spontaneous fission and electron capture (in order of most to least common types).
The appearance of this element is unknown, however it is most likely silvery-white or gray and metallic. If sufficient amounts of lawrencium were produced, it would pose a radiation hazard. Very little is known about the chemical properties of this element but some preliminary work on a few atoms has indicated that it behaves similarly to other actinides. Since only tiny amounts of lawrencium have ever been produced, there are currently no uses for it outside of basic scientific research.
A strict correlation between periodic table blocks and chemical series for neutral atoms would describe lawrencium as a transition metal because it is in the d-block, but it is an actinide according to IUPAC.
|Half-Life||Year Discovered||Discovery Reaction|
|252Lr||252.09537||390 ms||2001||209Bi(50Ti, 3n)|
|253Lr||253.09521||580 ms||1985||209Bi(50Ti, 2n)|
|253mLr||1.5 seconds||2001||209Bi(50Ti, 2n)|
|254Lr||254.09645||13 seconds||1985||209Bi(50Ti, n)|
|255Lr||255.09668||22 seconds||1970||243Am(16O, 4n)|
|256Lr||256.09863||27 seconds||1961? 1965? 1968? 1971||252Cf(10B, 6n)|
|257Lr||257.09956||0.646 seconds||1958? 1971||249Cf(15N, a3n)|
|258Lr||258.10181||4.1 seconds||1961? 1971||252Cf(15N, a2n)|
Atomic Radius (Å): unknown
Electrochemical Equivalent: 3.23g/amp-hr
Atomic Mass Average: 260
Produced by bombarding californium-252 with boron nuclei or BK-249 with O-18 nuclei. Few atoms of Lawrencium have ever been produced.
Molar Mass: 262.1 g/mol