Lawrencium
Definition and meaning of Lawrencium in chemistry.
Lawrencium is a synthetic radioactive element with the symbol Lr and atomic number 103. It represents the final element of the actinide series and is named in lasting honor of cyclotron inventor and physicist Ernest O. Lawrence.
In more detail
Lawrencium is synthesized entirely artificially by bombarding heavy actinide targets, such as californium, with fast-moving boron ions in a linear accelerator. It is strategically positioned at the absolute end of the f-block in the periodic table, meaning its atomic structure possesses a completely full 5f electron subshell. Exhaustive chemical experiments utilizing single-atom techniques have successfully confirmed that lawrencium predominantly behaves as a trivalent ion in aqueous solutions, analogous to the lighter actinides and the late lanthanides. Interestingly, some advanced atomic models and preliminary experiments suggest it might also display certain properties akin to a transition metal, largely due to intense relativistic effects altering the energy levels of its outermost valence electrons. Because it is incredibly radioactive and exists only very briefly in microscopic quantities, no macroscopic samples of pure lawrencium metal have ever been assembled.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Lr |
| Atomic number | 103 |
| Atomic mass | [266] u |
| Category | Actinide |
| State at room temperature | Solid (predicted) |
| Year discovered | 1961 at Berkeley |
| Melting point | 1900 K (predicted) |
| Ionization energy | 470 kJ/mol (predicted first ionization) |
Lawrencium is used exclusively for basic scientific research, particularly in sophisticated partition chromatography experiments to thoroughly investigate the chemical trends at the extreme end of the actinide series.
Frequently asked questions
Is lawrencium truly classified as an actinide or as a transition metal?
It is formally classified by IUPAC as the last actinide, though its ground-state electron configuration gives it some distinct characteristics similar to early group 3 transition metals.
What is the most stable known isotope of lawrencium today?
Lawrencium-266 is currently recognized as the most stable isotope, possessing a half-life of approximately 11 hours before undergoing spontaneous fission.