Lawrencium

group 3 · period 7 · d-block · actinide

Identity

Name and symbol: Lawrencium, Lr
Atomic number: 103 protons
Position: group 3 · period 7 · d-block · actinide
CAS number: 22537-19-5

Atomic structure

Atomic mass: 262 u
Electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 7p¹
[Rn] 7s²⁵f¹⁴⁶d¹
Electrons per shell: 2, 8, 18, 32, 32, 8, 3
Valence electrons: 3 ns and (n-1)d

nuclide	half-life	decay
²⁶⁶Lr	22 h	SF=100%
²⁶⁴Lr	10 h [Estimated]	α ?; SF ?
²⁶⁵Lr	10 h [Estimated]	α ?; SF ?
²⁶³Lr	5 h [Estimated]	α ?

no stable isotope; the longest-lived nuclides

Physical properties

State at room temperature: Solid
Melting point: 1,900 K (1,626.85 °C)
Boiling point: not in sources
Density: not in sources
Appearance: silvery (predicted)
Thermal conductivity: not in sources
Electrical resistivity: not in sources
Electrical conductivity: not in sources
Crystal structure: hexagonal close-packed
Molar heat capacity: not in sources

Chemical properties

Oxidation states: +3
Electronegativity: not in sources
Ionisation energy: 4.96 eV
1st 470 kJ/mol
Electron affinity: not in sources
Atomic radius: not in sources
Ionic radius: not in sources

Reactivity: The last actinide, known only from experiments on a few thousand atoms; it is trivalent in solution, Lr3+ about as stable as Lu3+, and every attempt to reduce it to Lr2+ or Lr+ in water has failed.
with water: Not known for the metal; in water lawrencium exists as the Lr3+ ion, ionic radius about 88 pm, eluting near erbium from cation-exchange columns.
with oxygen, air: Not known.
with acids: In acid solution extracts and elutes with the trivalent actinides, not with the divalent or tetravalent ones.
with halogens: Reacts with chlorine to a product that is most likely LrCl3, with volatility similar to the chlorides of curium, fermium and nobelium and much lower than rutherfordium chloride (1969 experiment).

Typical compounds: not in sources

Occurrence, production and use

Crustal abundance: Not Applicable
Oceanic abundance: Not Applicable

Occurrence and sources

synthetic only californium bombarded with boron

Extraction, production: not in sources

Uses: Since only tiny amounts of lawrencium have ever been produced, there are currently no uses for it outside of basic scientific research.

Safety, toxicity: not in sources

Discovery and name

Discovered by: Lawrence Berkeley National Laboratory and Joint Institute for Nuclear Research
Discovered: 1961 to 1971
First isolated: not in sources
Named by: not in sources
Origin of the name: after Ernest Lawrence

Lawrencium does not occur naturally in the Earth’s crust. Credit for the first synthesis of this element in 1971 is given jointly to Albert Ghiorso and his team at the University of California in Berkeley and Georgi Flerov and his team at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia (Fig. IUPAC.103.1). The element is named for Ernest O. Lawrence (Fig. IUPAC.103.2), who developed the cyclotron. The chemical symbol for lawrencium was originally proposed as Lw. At the IUPAC General Assembly in 1963, lawrencium was officially accepted by IUPAC, but the symbol was changed to Lr because the Commission on Inorganic Nomenclature determined that the letter ‘w’ presented a problem in languages other than English [636], [640], [641], [642]. There are no known isotopic applications for lawrencium outside of scientific research.

Lawrencium behaves differently from dipositive nobelium and more like the tripositive elements earlier in the actinide series.

Conventions

Valence electrons are counted by the usual convention: the outer shell for s- and p-block elements, ns and (n-1)d for the d-block, ns, (n-1)d and (n-2)f for the f-block. Lanthanides and actinides are placed in the f-block with no group number. Electrical conductivity is the reciprocal of the printed resistivity. Ionic radii are Shannon effective radii, six-coordinate unless noted. Where a field reads “not in sources” the value was not found; it is a gap, not a zero. Regulatory limits are the published values and change often, so check the standard in force at your site and the numbers written into your own permit before you design to them.

Data

Element records, isotopes, radii and the descriptive text come from PubChem (NCBI), the Los Alamos National Laboratory periodic table, IUPAC CIAAW and the IAEA Atomic Mass Data Center. Appearance, thermal conductivity, electrical resistivity, crystal structure, discovery and the origin of each name come from Wikipedia and Periodic-Table-JSON, used under CC BY-SA 4.0. Hazard classifications come from the ECHA C&L inventory via PubChem. Ionic radii follow R. D. Shannon (1976). The water chapters cite their own sources at the foot of each entry, and are written to the level of Snoeyink and Jenkins, Stumm and Morgan, MWH's Water Treatment and Metcalf and Eddy.