Stable isotope Erbium (Er)

Isotope Z(p) N(n) Atomic Mass Natural Abundance Enrichment Level Chemical Form
Er-162 68 94 161.928775 0.14% 28.20-39.20% Oxide
Er-164 68 96 163.929197 1.61% 51.30-75.30% Oxide
Er-166 68 98 165.930290 33.60% 94.70-98.10% Oxide
Er-167 68 99 166.932046 22.95% 95.30-96.30% Oxide
Er-168 68 100 167.932368 26.80% >98.00% Oxide
Er-170 68 102 169.935461 14.90% 97.70-98.20% Oxide

Properties of Erbium

Name Erbium
Symbol Er
Atomic number 68
Atomic weight 167.26
Standard state Solid at 298 ºK
CAS Registry ID 7440-52-0
Group in periodic table N/A
Group name Lanthanoid
Period in periodic table 6 (Lanthanoid)
Block in periodic table f-block
Color Silvery white
Classification Metallic
Melting point 1529 °C
Boiling point 2863 °C
Vaporization point 2863 ºC
Thermal conductivity 14.5 W/(m·K) at 298.2 °K
Electrical resistivity 107.0 µΩ·cm at 25 °C; 205 µΩ·cm at 1000 ºC
Electronegativity 1.2
Specific heat 0.168 J/g mol at 20 °C
Heat of vaporization 285 kJ·mol-1
Heat of fusion 19.9 kJ·mol-1
Density of liquid 8.86 g/cm3
Density of solid 9.07 g/cm3
Electron configuration [Xe]4f115d16s2
Atomic radius 1.758 Å (coordination number 12)
Atomic volume 18.49 cm3/mol
Oxidation states +2, +3