Erbium

Koushik 26/06/2026 19:58:08 Updated 26/06/2026 19:58:08

Property	Value
Atomic Number	68
Element	Erbium
Symbol	Er
Atomic Mass	167.259 u
Number of Neutrons	98 (most common isotope, Erbium-166)
Number of Protons	68
Number of Electrons	68
Period	6
Group	Lanthanide (no fixed group number)
Phase	Solid
Radioactive	No (some isotopes are radioactive)
Natural	Yes
Metal	Yes
Nonmetal	No
Metalloid	No
Type	Lanthanide
Atomic Radius	226 pm
Electronegativity	1.24 (Pauling scale)
First Ionization Energy	6.108 eV
Density	9.07 g/cm³
Melting Point	1529 °C
Boiling Point	2868 °C
Number of Isotopes	6 naturally occurring (Er-162, Er-164, Er-166, Er-167, Er-168, Er-170)
Discoverer	Carl Gustaf Mosander
Year	1843
Specific Heat	0.168 J/g·K
Number of Shells	6
Number of Valence Electrons	3