Lawrencium
Synthetic actinide element named after cyclotron inventor Ernest Lawrence.
It is named after Ernest Lawrence, inventor of the cyclotron, a device used to discover many artificial radioactive elements. A radioactive metal, lawrencium is the eleventh transuranium element, the third transfermium, and the last member of the actinide series.
- symbol
- Lr (formerly Lw)
- element_type
- synthetic, radioactive metal
- series
- actinide series
- named_after
- Ernest Lawrence
- most_stable_isotope
- 266Lr (half-life 11 hours)
- common_isotope_for_chemistry
- 260Lr (half-life 2.7 minutes)
Lore & Background
The first atoms of lawrencium were reportedly made by bombarding a three-milligram target consisting of three isotopes of californium with boron-10 and boron-11 nuclei from the Heavy Ion Linear Accelerator (HILAC). The Berkeley team reported that the isotope 257Lr was detected, decaying by emitting an 8.6 MeV alpha particle with a half-life of 8±2 s; this identification was later corrected to 258Lr. The Berkeley team proposed the name 'lawrencium' with symbol 'Lw', after Ernest Lawrence. The IUPAC Commission on Nomenclature of Inorganic Chemistry accepted the name but changed the symbol to 'Lr'.
Reader's Guide
Lawrencium's discovery was disputed between Soviet and American scientists. The name 'lawrencium' was retained. Chemistry experiments confirm that lawrencium behaves as a heavier homolog to lutetium in the periodic table and is trivalent. Its electron configuration is anomalous for its position, having an s2p configuration instead of the s2d configuration of lutetium, though this does not appear to affect its chemistry. Lawrencium is expected to be a solid under normal conditions and have a hexagonal close-packed crystal structure, similar to lutetium. It is the last actinide and is considered a group 3 element, along with scandium, yttrium, and lutetium.
Did You Know?
- Lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles.
- The most stable isotope is 266Lr with a half-life of 11 hours, but 260Lr (half-life 2.7 minutes) is most commonly used in chemistry.
- Lawrencium's electron configuration is s2p instead of the s2d configuration of its homolog lutetium.
Frequently Asked Questions
Who is Lawrencium named after?
Lawrencium honors Ernest Lawrence, the physicist who invented the cyclotron. His particle accelerator was instrumental in producing many of the artificial radioactive elements that follow the naturally occurring ones.
Where does Lawrencium sit on the periodic table?
It is the eleventh transuranium element and the third transfermium element. It also serves as the final member of the actinide series, closing out that row of heavy elements.
What is Lawrencium's most stable isotope?
The longest-lived isotope is 266Lr, which has a half-life of roughly eleven hours. Like all known isotopes of the element, it decays radioactively and cannot persist for any meaningful duration.
Why do periodic-table fans consider Lawrencium a milestone?
As the last actinide, it marks the boundary where the f-block ends and the next series of elements begins. Its discovery also showcased the cyclotron's power, tying the element's identity directly to the instrument that made it possible.
More in Periodic Table & Elements 1-21
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