Lawrencium

Lawrencium is a synthetic chemical element with chemical symbol Lr (formerly Lw) and atomic number 103. It is named in honor of Ernest Lawrence, inventor of the cyclotron, a device that was used to discover many artificial radioactive elements. A radioactive metal, lawrencium is the eleventh transuranic element and is also the final member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles. Eleven isotopes of lawrencium are currently known; the most stable is ²⁶²Lr with a half-life of 3.6 hours, but the shorter-lived ²⁶⁰Lr (half-life 2.7 minutes) is most commonly used in chemistry because it can be produced on a larger scale. A new isotope, ²⁶⁶Lr, with a half-life of 11 hours has been reported but not confirmed.

Chemistry experiments have confirmed that lawrencium indeed behaves as a heavier homolog to lutetium in the periodic table, and is a trivalent element. It thus could also be classified as the first of the 7th-period transition metals: however, its electron configuration is anomalous for its position in the periodic table, having an s²p configuration instead of the s²d configuration of its homolog lutetium. This means that lawrencium may be less volatile than expected for its position in the periodic table and have a volatility comparable to that of lead.

Isotopes of lawrencium

Lawrencium (Lr) is a synthetic element, and thus a standard atomic mass cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was ²⁵⁸Lr in 1961. There are twelve known radioisotopes from ²⁵²Lr to ²⁶⁶Lr, and 1 isomer (^253mLr). The longest-lived isotope is ²⁶⁶Lr with a half-life of 11 hours. Heavier isotopes are expected to have longer half-lives.

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