Lawrencium | |||||||||||||||||||||||||||||||||||||||||||||
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Pronunciation | /lɒˈrɛnsiəm/ | ||||||||||||||||||||||||||||||||||||||||||||
Appearance | silvery (predicted)[1] | ||||||||||||||||||||||||||||||||||||||||||||
Mass number | [266] (data not decisive)[a] | ||||||||||||||||||||||||||||||||||||||||||||
Lawrencium in the periodic table | |||||||||||||||||||||||||||||||||||||||||||||
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Atomic number (Z) | 103 | ||||||||||||||||||||||||||||||||||||||||||||
Group | group 3 | ||||||||||||||||||||||||||||||||||||||||||||
Period | period 7 | ||||||||||||||||||||||||||||||||||||||||||||
Block | d-block | ||||||||||||||||||||||||||||||||||||||||||||
Electron configuration | [Rn] 5f14 7s2 7p1 | ||||||||||||||||||||||||||||||||||||||||||||
Electrons per shell | 2, 8, 18, 32, 32, 8, 3 | ||||||||||||||||||||||||||||||||||||||||||||
Physical properties | |||||||||||||||||||||||||||||||||||||||||||||
Phase at STP | solid (predicted) | ||||||||||||||||||||||||||||||||||||||||||||
Melting point | 1900 K (1600 °C, 3000 °F) (predicted) | ||||||||||||||||||||||||||||||||||||||||||||
Density (near r.t.) | 14.4 g/cm3 (predicted)[4] | ||||||||||||||||||||||||||||||||||||||||||||
Atomic properties | |||||||||||||||||||||||||||||||||||||||||||||
Oxidation states | +3 | ||||||||||||||||||||||||||||||||||||||||||||
Electronegativity | Pauling scale: 1.3 (predicted)[5] | ||||||||||||||||||||||||||||||||||||||||||||
Ionization energies |
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Other properties | |||||||||||||||||||||||||||||||||||||||||||||
Natural occurrence | synthetic | ||||||||||||||||||||||||||||||||||||||||||||
Crystal structure | hexagonal close-packed (hcp) (predicted)[7] | ||||||||||||||||||||||||||||||||||||||||||||
CAS Number | 22537-19-5 | ||||||||||||||||||||||||||||||||||||||||||||
History | |||||||||||||||||||||||||||||||||||||||||||||
Naming | after Ernest Lawrence | ||||||||||||||||||||||||||||||||||||||||||||
Discovery | Lawrence Berkeley National Laboratory and Joint Institute for Nuclear Research (1961–1971) | ||||||||||||||||||||||||||||||||||||||||||||
Isotopes of lawrencium | |||||||||||||||||||||||||||||||||||||||||||||
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Lawrencium is a synthetic chemical element; it has symbol Lr (formerly Lw) and atomic number 103. It is named after Ernest Lawrence, inventor of the cyclotron, a device that was 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. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles. Fourteen isotopes of lawrencium are currently known; the most stable is 266Lr with half-life 11 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.
Chemistry experiments confirm that lawrencium 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. 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. However, this does not appear to affect lawrencium's chemistry.
In the 1950s, 1960s, and 1970s, many claims of the synthesis of element 103 of varying quality were made from laboratories in the Soviet Union and the United States. The priority of the discovery and therefore the name of the element was disputed between Soviet and American scientists. The International Union of Pure and Applied Chemistry (IUPAC) initially established lawrencium as the official name for the element and gave the American team credit for the discovery; this was reevaluated in 1992, giving both teams shared credit for the discovery but not changing the element's name.
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