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Element: Lanthanum

General data

Element nameLanthanum
Chemical symbolLa
Atomic number Z57
Year discovered1839
Standard state (25°C)Solid
CategoryLanthanide
Blockf
Atomic mass138.91
CPK color#70D4FF

Physical properties

Melting point1191 K (918 °C)
Boiling point3737 K (3464 °C)
Density6.15 g/cm³

Energy properties

First ionization energy5.577 eV
Electron affinity0.5 eV

Atomic structure

Protons57 (Atomic number)
Neutrons (La-139, most abundant isotope)82
Electrons57
Electron configuration[Xe] 6s² 5d¹
Oxidation states+3
Electronegativity (Pauling)1.1
Atomic radius (van der Waals)240 pm

Ionization energies - NIST ASD (57 states)

StateChargeIoniz. energy (eV)Type
La I0+5.5769 ± 0.0006measured
La II1+11.18496 ± 0.00006measured
La III2+19.1773 ± 0.0006measured
La IV3+49.95 ± 0.06semi-empirical
La V4+61.6 ± 0.6semi-empirical
La VI5+74 ± 2calculated
La VII6+88 ± 2calculated
La VIII7+105 ± 2.1calculated
La IX8+119 ± 2.2calculated
La X9+151.4 ± 0.7semi-empirical
La XI10+168.77 ± 0.12semi-empirical
La XII11+275 ± 2.5calculated
La XIII12+303 ± 3calculated
La XIV13+332 ± 3calculated
La XV14+364 ± 3calculated
La XVI15+393 ± 3calculated
La XVII16+431 ± 3calculated
La XVIII17+464 ± 3calculated
La XIX18+498 ± 3calculated
La XX19+533 ± 4calculated
La XXI20+566 ± 4calculated
La XXII21+696 ± 4calculated
La XXIII22+731 ± 4calculated
La XXIV23+770 ± 4calculated
La XXV24+806 ± 4calculated
La XXVI25+865 ± 4calculated
La XXVII26+906 ± 4calculated
La XXVIII27+995 ± 4calculated
La XXIX28+1039.09 ± 0.12semi-empirical
La XXX29+1800 ± 4calculated
La XXXI30+1884 ± 4calculated
La XXXII31+1974 ± 4calculated
La XXXIII32+2069 ± 4calculated
La XXXIV33+2162 ± 5calculated
La XXXV34+2259 ± 5calculated
La XXXVI35+2377 ± 5calculated
La XXXVII36+2473 ± 5calculated
La XXXVIII37+2577 ± 4calculated
La XXXIX38+2674 ± 4calculated
La XL39+2950 ± 4calculated
La XLI40+3036 ± 4calculated
La XLII41+3133 ± 4calculated
La XLIII42+3222 ± 4calculated
La XLIV43+3416 ± 4calculated
La XLV44+3515 ± 4calculated
La XLVI45+3704 ± 4calculated
La XLVII46+3800 ± 4calculated
La XLVIII47+8669 ± 4calculated
La XLIX48+8914 ± 4calculated
La L49+9184 ± 4calculated
La LI50+9437 ± 4calculated
La LII51+10136 ± 4calculated
La LIII52+10426 ± 4calculated
La LIV53+10789 ± 5calculated
La LV54+11033.4 ± 0.05calculated
La LVI55+45145 ± 0.04calculated
La LVII56+46245.77 ± 0.03calculated

Value type as given by NIST ASD: measured - from evaluated experimental data; calculated - from ab initio calculations (mostly highly ionised atoms that have not been measured; for the simplest ones, e.g. H I, the calculation is more accurate than measurement); semi-empirical - from interpolation, extrapolation or another semi-empirical method.

Photos

Photo of the element: Lanthanum (La)
© images-of-elements.com (CC BY 3.0)

Isotopes (39)

ANHalf-lifeDecay
La-1176021.7 msp
La-120632.8 sEC/β⁺
La-121645.3 sEC/β⁺
La-122658.7 sEC/β⁺
La-1236616.3 sEC/β⁺
La-1246721 sEC/β⁺
La-1256864.8 sEC/β⁺
La-1266954 sEC/β⁺
La-127705.1 minEC/β⁺
La-128715.1 minEC/β⁺
La-1297211.6 minEC/β⁺
La-130738.7 minEC/β⁺
La-1317459 minEC/β⁺
La-132754.58 hEC/β⁺
La-133763.89 hEC/β⁺
La-134776.45 minEC/β⁺
La-1357818.95 hEC/β⁺
La-136799.87 minEC/β⁺
La-1378060000 aEC
La-138811.028×10¹¹ aβ⁻
La-13982stable-
La-1408340.284 hβ⁻
La-141843.93 hβ⁻
La-1428591.8 minβ⁻
La-1438614.09 minβ⁻
La-1448740.8 sβ⁻
La-1458824.8 sβ⁻
La-146896.1 sβ⁻
La-147904.024 sβ⁻
La-148911.41 sβ⁻
La-149921.09 sβ⁻
La-150930.510 sβ⁻
La-151940.46 sβ⁻
La-15295298 msβ⁻
La-15396244 msβ⁻
La-15497163 msβ⁻
La-15598100 msβ⁻
La-1569980 msβ⁻
La-157100unknownβ⁻

Data sources

More about the data sources