Lanthanum, 57 La Lanthanum Pronunciation (LAN -thə-nəm ) Appearance sillery white Standard atomic weight A r, std (La) 7002138905470000000♠ 138.90547 (7)[ 1] Lanthanum in the periodic cairt
Atomic nummer (Z ) 57 Group group 3 Period period 6 Block f-block Element category Lanthanide Electron confeeguration [Xe ] 5d1 6s2 Electrons per shell 2, 8, 18, 18, 9, 2 Pheesical properties Phase at STP solit Meltin pynt 1193 K (920 °C, 1688 °F) Bylin pynt 3737 K (3464 °C, 6267 °F) Density (near r.t. ) 6.162 g/cm3 when liquid (at m.p. ) 5.94 g/cm3 Heat o fusion 6.20 kJ/mol Heat o vapourisation 402.1 kJ/mol Molar heat capacity 27.11 J/(mol·K) Vapour pressur (extrapolated)
P (Pa)
1
10
100
1 k
10 k
100 k
at T (K)
2005
2208
2458
2772
3178
3726
Atomic properties Oxidation states 0,[ 2] +1, +2, +3 strangly basic Electronegativity Pauling scale: 1.10 Atomic radius empirical: 187 pm Covalent radius 207±8 pm Colour lines in a spectral range Spectral lines o lanthanumIther properties Naitural occurrence primordial Creestal structur hexagonal Speed o soond thin rod 2475 m/s (at 20 °C) Thermal expansion (r.t. ) (α, poly) 12.1 µm/(m·K) Thermal conductivity 13.4 W/(m·K) Electrical resistivity (r.t. ) (α, poly) 615 n Ω·m Magnetic orderin paramagnetic [ 3] Young's modulus (α form) 36.6 GPa Shear modulus (α form) 14.3 GPa Bulk modulus (α form) 27.9 GPa Poisson ratio (α form) 0.280 Mohs haurdness 2.5 Vickers haurdness 491 MPa Brinell haurdness 363 MPa CAS Nummer 7439-91-0 History Diskivery Carl Gustaf Mosander (1838) Main isotopes o lanthanum
Decay modes in parentheses are predicted, but hisna yet been observed | references
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C
920
—
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K
1193
1190
3
delta
F
1688
1690
-2
delta
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C: 920, K: 1193, F: 1688
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in
calc from C
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C
3464
—
—
K
3737
3737
0
F
6267
6267
0
WD
String Module Error: Target string is empty !
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C: 3464, K: 3737, F: 6267
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References
Thir references will appear in the airticle, but this list appears anerly on this page.
↑ Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)" . Pure and Applied Chemistry . 88 (3): 265–91. doi :10.1515/pac-2015-0305 .
↑ Yttrium and all lanthanides except Ce, Pm, Eu, Tm, Yb 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 .
↑ Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics (PDF) . CRC press. 2000. ISBN 0849304814 .