SymbolLa
Latin nameLanthanium
Atomic number57
Period6
Element categoryTransition elements
Relative atomic mass138.9055
GroupIII.B
Electronegativity
1.1
Oxidation numbers
3
Electron configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 5d1 6s2
Density [g/cm3]
6.166
State
Solid
Melting point [°C]
921
Boiling point [°C]
3457
Covalent radius [pm]
169
Thermal conductivity [W m-1K-1]
13.5
Heat capacity [J K-1g-1]
0.19
Discovery
1839
Hardness [Mohs scale]
2.5
Vickers hardness [MPa]
491
Brinell hardness [MPa]
363
Young's modulus [GPa]
37
Electrical conductivity [S m-1]
1.9 · 106
Shear modulus [GPa]
14
1.st ionization energy [eV]
5.577
2.nd ionization energy [eV]
11.059
3.rd ionization energy [eV]
19.174
Stable isotopes
2
Unstable isotopes
16