103
  Lr  
262.000000
Lawrencium

Name: Lawrencium
Symbol: Lr
Atomic Number: 103
Atomic Weight: 262.000000
Family: Rare Earth Elements
CAS RN: 22537-19-5
Description: A synthetic rare earth metal, not present in nature.
State (25C): Unknown (Synthetic)
Oxidation states: +3

Molar Volume: unknown
Valence Electrons: 5f146d17s2

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
Density: unknown
Specific Heat: unknown
Atomic Radius: unknown
Ionic Radius: 88pm
Electronegativity: 1.3
89
Ac
227.0
90
Th
232.0
91
Pa
231.0
92
U
238.0
93
Np
237.0
94
Pu
(244)
95
Am
(243)
96
Cm
(247)
97
Bk
(247)
98
Cf
(251)
99
Es
(252)
100
Fm
(257)
101
Md
(258)
102
No
(259)
103
Lr
(260)
1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10f14 6s2p6d17s2

History

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.

lawrence.jpg (55490 bytes)

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).

Characteristics

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.

1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d10 5f14
6s2 6p6 6d1
7s2

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.

Isotopes 

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Isotope  
Atomic Mass
 
Half-Life Year Discovered Discovery Reaction
251Lr 251.09436 ~150 s    
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)
259Lr 259.10290 6.2 seconds 1971 248Cm(15N,4n)
260Lr 260.10550 3.0 minutes 1971 248Cm(15N,3n)
261Lr 261.10688 39 minutes 1987 254Es+22Ne
262Lr 262.10963 216 minutes 1987 254Es+22Ne
263Lr 263.11129 ~5 hours    
264Lr 264.11404 ~10 hours    
265Lr 265.11584 ~10 hours    
266Lr 266.11931 ~1 hours    

atom.gif (700 bytes)

Lawrencium Data

 

Atomic Structure

Atomic Radius (): unknown
Atomic Volume: unknown
Covalent Radius: unknown
Crystal Structure: unknown
Ionic Radius: unknown

Chemical Properties

Electrochemical Equivalent: 3.23g/amp-hr
Electron Work Function: unknown
Electronegativity: 1.3
Heat of Fusion: unknown
First Ionization Energies: 443.8 kJ/mol
Second Ionization Energies: 1428.0 kJ/mol
Third Ionization Energies: 2219.1 kJ/mol

Physical Properties

Atomic Mass Average: 260
Boiling Point: unknown
Melting Point: 1900oK, 1626oC, 2961oF
Heat of Vaporization: unknown
Coefficient of Lineal Thermal Expansion/K-1:
Electrical Conductivity: unknown
Thermal Conductivity: 0.1 W/cmK
Density: unknown
Enthalpy of Atomization: unknown
Enthalpy of Fusion: unknown
Enthalpy of Vaporization: unknown
Molar Volume: unknown
Specific Heat: unknown
Vapor Pressure: unknown
Estimated Crustal Abundance: unknown
Estimated Oceanic Abundance: unknown

Miscellaneous

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