Lanthanum, 57La
Lanthanum
Pronunciation/ˈlænθənəm/ (LAN-thə-nəm)
Appearancesilvery white
Standard atomic weight Ar°(La)
Lanthanum 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


La

Ac
bariumlanthanumcerium
Atomic number (Z)57
Groupf-block groups (no number)
Periodperiod 6
Block  f-block
Electron configuration[Xe] 5d1 6s2
Electrons per shell2, 8, 18, 18, 9, 2
Physical properties
Phase at STPsolid
Melting point1193 K ​(920 °C, ​1688 °F)
Boiling point3737 K ​(3464 °C, ​6267 °F)
Density (at 20° C)6.145 g/cm3[3]
when liquid (at m.p.)5.94 g/cm3
Heat of fusion6.20 kJ/mol
Heat of vaporization400 kJ/mol
Molar heat capacity27.11 J/(mol·K)
Vapor pressure (extrapolated)
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 2005 2208 2458 2772 3178 3726
Atomic properties
Oxidation statescommon: +3
0,[4] +1,[5] +2[6]
ElectronegativityPauling scale: 1.10
Ionization energies
  • 1st: 538.1 kJ/mol
  • 2nd: 1067 kJ/mol
  • 3rd: 1850.3 kJ/mol
Atomic radiusempirical: 187 pm
Covalent radius207±8 pm
Color lines in a spectral range
Spectral lines of lanthanum
Other properties
Natural occurrenceprimordial
Crystal structureα form: ​double hexagonal close-packed (dhcp) (hP4)
Lattice constants
Double hexagonal close packed crystal structure for α form: lanthanum
a = 0.37742 nm
c = 1.2171 nm (at 20 °C)[3]
Thermal expansion5.1×10−6/K (at 20 °C)[3][a]
Thermal conductivity13.4 W/(m⋅K)
Electrical resistivityα, poly: 615 nΩ⋅m (at r.t.)
Magnetic orderingparamagnetic[7]
Molar magnetic susceptibility+118.0×10−6 cm3/mol (298 K)[8]
Young's modulusα form: 36.6 GPa
Shear modulusα form: 14.3 GPa
Bulk modulusα form: 27.9 GPa
Speed of sound thin rod2475 m/s (at 20 °C)
Poisson ratioα form: 0.280
Mohs hardness2.5
Vickers hardness360–1750 MPa
Brinell hardness350–400 MPa
CAS Number7439-91-0
History
DiscoveryCarl Gustaf Mosander (1838)
Isotopes of lanthanum
Main isotopes[9] Decay
abun­dance half-life (t1/2) mode pro­duct
137La synth 6×104 y ε 137Ba
138La 0.089% 1.03×1011 y ε 138Ba
β 138Ce
139La 99.911% stable
 Category: Lanthanum
| references
La · Lanthanum
Ba ←

ibox Ba

iso
57
La  [e]
IB-La [e]
IBisos [e]
→ Ce

ibox Ce

indexes by PT (page)
child table, as reused in {IB-La}
Main isotopes of lanthanum
Main isotopes[9] Decay
abun­dance half-life (t1/2) mode pro­duct
137La synth 6×104 y ε 137Ba
138La 0.089% 1.03×1011 y ε 138Ba
β 138Ce
139La 99.911% stable
Data sets read by {{Infobox element}}
Name and identifiers
Symbol etymology (11 non-trivial)
Top image (caption, alt)
Pronunciation
Allotropes (overview)
Group (overview)
Period (overview)
Block (overview)
Natural occurrence
Phase at STP
Oxidation states
Spectral lines image
Electron configuration (cmt, ref)
Isotopes
Standard atomic weight
  most stable isotope
Wikidata
Wikidata *
* Not used in {{Infobox element}} (2023-01-01)
See also {{Index of data sets}} · Cat:data sets (46) · (this table: )

Notes

  1. ^ The thermal expansion of α-La is anisotropic: the parameters (at 20 °C) for each crystal axis are αa = 2.9×10−6/K, αc = 9.5×10−6/K, and αaverage = αV/3 = 5.1×10−6/K.[3]

References

  1. ^ "Standard Atomic Weights: Lanthanum". CIAAW. 2005.
  2. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. ^ a b c d Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  4. ^ Yttrium and all lanthanides except Ce and Pm have been observed in the oxidation state 0 in bis(1,3,5-tri-t-butylbenzene) complexes, see Cloke, F. Geoffrey N. (1993). "Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides". Chem. Soc. Rev. 22: 17–24. doi:10.1039/CS9932200017. and Arnold, Polly L.; Petrukhina, Marina A.; Bochenkov, Vladimir E.; Shabatina, Tatyana I.; Zagorskii, Vyacheslav V.; Cloke (2003-12-15). "Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation". Journal of Organometallic Chemistry. 688 (1–2): 49–55. doi:10.1016/j.jorganchem.2003.08.028.
  5. ^ La(I), Pr(I), Tb(I), Tm(I), and Yb(I) have been observed in MB8 clusters; see Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng (2021). "Monovalent lanthanide(I) in borozene complexes". Nature Communications. 12 (1): 6467. doi:10.1038/s41467-021-26785-9. PMC 8578558. PMID 34753931.
  6. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
  7. ^ Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
  8. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  9. ^ a b Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.