Latin nameLanthanium
English nameLanthanum
chemical symbolLa
atomic number57
relative atomic mass138,9055
classificationtransition metals
discovery year1839
discovererC. G. Mosander
melting point [°C]918
boiling point [°C]3464
density [g cm-3]6,7
density at melting point [g cm-3]5,94
electronegativity [Pauling]1,1
oxidation statesIII
electron configuration[Xe]5d1 6s2
covalent radius [pm]169
specific heat [J g-1K-1]0,19
heat of fusion [kJ mol-1]6,2
thermal conductivity [W m-1 K-1]13,4
el. conductivity [S m-1]1,9.106
1. ionizing potential [eV]5,577
2. ionizing potential [eV]11,059
3. ionizing potential [eV]19,174
Mohs hardness2,5
Vickers hardness [MPa]491
Brinell hardness [MPa]363
shear modulus [GPa]14
Young's modulus [GPa]37
point of superconductivity [K]4,88
state at normal conditionssolid

Lanthanum is silvery white, malleable, ductile, and soft metal.