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|Atomic Number:||103||Atomic Symbol:||Lr|
|Atomic Weight:||262||Electron Configuration:||2-8-18-32-32-9-2|
|Melting Point:||oC||Boiling Point:||oC|
|Description:||Man made radioactive metal.|
History(Ernest O. Lawrence, inventor of the cyclotron)
- This member of the 5f transition elements (actinide series) was discovered
in March 1961 by A. Ghiorso, T. Sikkeland, A.E. Larsh, and R.M. Latimer.
- A 3-Mg californium target, consisting of a mixture of isotopes of mass
number 249, 250, 251, and 252, was bombarded with either 10B or 11B.
- The electrically charged transmutation nuclei recoiled with an atmosphere of
helium and were collected on a thin copper conveyor tape which was then moved to
place collected atoms in front of a series of solid-state detectors.
- The isotope of element 103 produced in this way decayed by emitting an 8.6
MeV alpha particle with a half-life of 8 s.
- In 1967, Flerov and associates at the Dubna Laboratory reported their
inability to detect an alpha emitter with a half-life of 8 s which was assigned
by the Berkeley group to 257-103.
- This assignment has been changed to 258Lr or 259Lr.
- In 1965, the Dubna workers found a longer-lived lawrencium isotope, 256Lr,
with a half-life of 35 s.
- In 1968, Thiorso 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 s.
PropertiesLawrencium behaves differently from dipositive nobelium and
more like the tripositive elements earlier in the actinide series.