Lawrencium

Lawrencium, ₁₀₃Lr

Lawrencium
Pronunciation	/lɒˈrɛnsiəm/ ⓘ ​(lo-REN-see-əm)
Appearance	silvery (predicted)[1]
Mass number	[266] (data not decisive)[a]
Lawrencium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Lu ↑ Lr ↓ — nobelium ← lawrencium → rutherfordium
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	common: +3
Electronegativity	Pauling scale: 1.3 (predicted)[5]
Ionization energies	1st: 479 kJ/mol[6] 2nd: 1428.0 kJ/mol (predicted) 3rd: 2219.1 kJ/mol (predicted)
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 v e
Main isotopes[2] Decay abun­dance half-life (t1/2) mode pro­duct 256Lr synth 27.9 s α 252Md β+ 256No 260Lr synth 3.0 min α 256Md β+ 260No 261Lr synth 39 min SF – 262Lr synth 4 h β+ 262No 264Lr synth 4.8 h[3] SF – 266Lr synth 11 h SF –
Category: Lawrencium view talk edit | references

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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