Stable isotope Lanthanum (La)

Isotope Z(p) N(n) Atomic Mass Natural Abundance Enrichment Level Chemical Form
La-138 57 81 137.90711 0.09% 5.90% Oxide
La-139 57 82 138.906349 99.91% 99.99% Oxide

Properties of Lanthanum

Name Lanthanum
Symbol La
Atomic number 57
Atomic weight 138.91
Standard state Solid at 298 °K
CAS Registry ID 7439-91-0
Group in periodic table N/A
Group name Lanthanoid
Period in periodic table 6
Block in periodic table f-block
Color Silvery white
Classification Metallic
Melting point 918 °C
Boiling point 3457 °C
Vaporization point 3464 ºC
Thermal conductivity 13.4 W/(m·K) at 298.2 °K
Electrical resistivity 5.70 µΩ·cm at 25 °C
Electronegativity 1.17
Specific heat 0.19 J/(g·K)
Heat of vaporization 400 kJ·mol-1 at 3457 °C
Heat of fusion 6.2 kJ·mol-1
Density of liquid 5.94 g/cm3 at 918 °C
Density of solid 6.166 g/cm3
Electron configuration [Xe]5d16s2
Atomic radius 1.879 Å
Ionic radius La3+:  1.061 Å
Oxidation state +3