68ErErbium167.2593[Xe] 4f¹² 6s²
lanthanide

Erbium

Erbium is a chemical element in the lanthanide series, with symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements on Earth. As such, it is a rare earth element which is associated with several other rare elements in the mineral gadolinite from Ytterby in Sweden, where yttrium, ytterbium, and terbium were discovered.

Electronic structure

A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.

Electrons by shell
Electron configuration
4f12
6s2

54 is the [Xe] core total across five shells.

Properties

At a glance

Atomic number
68
Atomic mass
167.2593 u
Phase
Solid
Density
9.066 g/cm³
Melting point
1,802 K
Boiling point
3,141 K
First ionization energy
589.3 kJ/mol
Electronegativity
1.24
Electron affinity
30.1 kJ/mol
Molar heat capacity
28.12 J/(mol·K)
Period
6
Appearance
silvery white

Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.

Keep exploring

Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.