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Name , symbol , atomic number Lawrencium, Lr, 103
Element category Actinoids
Group , period , block Ac , 7 , f
CAS number 22537-19-5
Atomic mass 266 u
Electron configuration [ Rn ] 5 f 14 6 d 1 7 s 2 (?)
[Rn] 5f 14 7s 2 7p 1 (?)
1. Ionization energy 4th.96 (8) eV479 kJ / mol
2. Ionization energy 14th.54 (4) eV1 400 kJ / mol
3. Ionization energy 21st.80 (4) eV2 100 kJ / mol
4. Ionization energy 43.6 (4) eV4 210 kJ / mol
5. Ionization energy 56.0 (1.9) eV5 400kJ / mol
Physical state firmly
Oxidation states +3
isotope NH t 1/2 ZA ZE (M eV ) ZP
260 Lr {syn.} 180 s α 8.310 256 billion
ε 2.740 260 No.
261 Lr {syn.} 39 min SF
262 Lr {syn.} 3.6 h ε 2.100 262 No.
266 Lr {syn.} 11 h SF
For other isotopes see list of isotopes
Hazard and safety information
GHS hazard labeling
no classification available
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions .

Lawrencium ( listen ? / I ) is an exclusively artificially produced chemical element with the element symbol Lr and the ordinal number 103. In the periodic table it is in the group of actinides ( 7th period , f-block ) and is also one of the transuranic elements . Lawrencium is a radioactive metal, which, however, has not been represented as a metal due to the small quantities available. It was discovered in 1961 when californium was bombarded with boron cores. This element was named after Ernest Lawrence . He is the inventor of the cyclotron , a particle accelerator that was an important prerequisite for the discovery of many transuranic elements. The name was finally confirmed by the IUPAC in 1994 . Audio file / audio sample


Ernest Orlando Lawrence
Albert Ghiorso (2nd from left) completing the periodic table after the discovery of the Lawrencium (1961), at that time still with the element symbol "Lw".

Lawrencium was first produced in 1961 by the American scientists Albert Ghiorso , Torbjørn Sikkeland , Almon E. Larsh and Robert M. Latimer by bombarding californium isotopes with nuclei of boron atoms. On February 14, 1961, they announced the successful synthesis of the element.

Initially, the symbol “Lw” was chosen. In 1963 it was changed to "Lr" by IUPAC ( International Union for Pure and Applied Chemistry ).


In the periodic table , the Lawrencium with the ordinal number 103 is in the series of the actinides and closes them off. Its predecessor is nobelium , the subsequent element is rutherfordium , which, however, already belongs to the transactinoids and is a d element. Its analogue in the series of lanthanides is the lutetium , which also closes this.

Lawrencium is a radioactive and very short-lived metal. Twelve isotopes are known with half-lives ranging from a few seconds to 11 hours. Little is known about other properties of the element, as the short half-life makes empirical studies almost impossible.

The position of Lawrencium in the periodic table is controversial, since recent measurements show that the element has an extremely low ionization energy.

safety instructions

Classifications according to the CLP regulation are not available because they only include chemical hazard, which plays a completely subordinate role compared to the hazards caused by radioactivity . The latter also only applies if the amount of substance involved is relevant.


Web links

Commons : Lawrencium  - collection of images, videos and audio files
Wiktionary: Lawrencium  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. The values ​​of the atomic and physical properties (infobox) are, unless otherwise stated, taken from: Robert J. Silva: Fermium, Mendelevium, Nobelium, and Lawrencium , in: Lester R. Morss, Norman M. Edelstein, Jean Fuger ( Ed.): The Chemistry of the Actinide and Transactinide Elements , Springer, Dordrecht 2006; ISBN 1-4020-3555-1 , pp. 1621-1651.
  2. a b c d e entry on lawrencium in Kramida, A., Ralchenko, Yu., Reader, J. and NIST ASD Team (2019): NIST Atomic Spectra Database (ver. 5.7.1) . Ed .: NIST , Gaithersburg, MD. doi : 10.18434 / T4W30F ( ). Retrieved June 13, 2020.
  3. a b c d e entry on lawrencium at WebElements, , accessed on June 13, 2020.
  4. The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling. With regard to other hazards, this element has either not yet been classified or a reliable and citable source has not yet been found.
  5. ^ Names and Symbols of Transfermium Elements (IUPAC Recommendations 1994). (PDF; 172 kB).
  6. ^ Albert Ghiorso, Torbjørn Sikkeland, Almon E. Larsh, Robert M. Latimer: New Element, Lawrencium, Atomic Number 103 , in: Phys. Rev. Lett. , 1961 , 6  (9), pp. 473-475 ( doi: 10.1103 / PhysRevLett.6.473 ).
  7. ^ The History of the Lawrencium , accessed on February 13, 2011.