ElementsWhat is erbium?
Erbium is a soft, silvery metal of the lanthanide row. Its salts are pink.
What is erbium used for?
Amplifiers in fibre-optic cables that carry internet traffic, skin and dental lasers, and pink glass.
Where the name comes from
From Ytterby, the village in Sweden.
Key facts
- Symbol
- Er
- Atomic number
- 68
- Atomic mass
- 167.26 u
- Family
- Lanthanide
- Period
- 6
- Group
- none (f-block)
- Block
- f
- State at room temperature
- Solid
- Melting point
- 1,529 °C (1,802 K, 2,784 °F)
- Boiling point
- 2,868 °C (3,141 K, 5,194 °F)
- Density
- 9.07 g/cm³
- Electrons per shell
- 2, 8, 18, 30, 8, 2
- Electron configuration
- [Xe]6s2 4f12
- Common oxidation states
- +3
- Electronegativity (Pauling)
- 1.24
- First ionisation energy
- 6.108 eV
- Electron affinity
- no value
- Atomic radius (van der Waals)
- 235 pm
- Discovered
- 1843
Place in the periodic table
Erbium is element number 68. It sits in period 6 (row 6) of the periodic table, in the separate row of lanthanides drawn below the main table, and belongs to the f-block. Just before it comes holmium (67), and just after it comes thulium (69).
Family: Lanthanides.
Physical properties
At room temperature erbium is a solid. It melts at 1,529 °C and boils at 2,868 °C, so it stays liquid over a range of 1,339 degrees. Its density is 9.07 grams per cubic centimetre, so a one-litre block would weigh about 9.07 kilograms. By density it ranks 31st among the 96 elements with a measured value.
Inside the atom
An atom of erbium has 68 protons in its nucleus and, when neutral, 68 electrons around it. The electrons are arranged in 6 shells: 2, 8, 18, 30, 8, 2. The outermost shell holds 2 electrons. Written in full, the electron configuration is [Xe]6s2 4f12.
Its electronegativity on the Pauling scale is 1.24. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 6.108 electronvolts (about 589 kilojoules per mole). One mole of erbium weighs 167.26 grams, so a single gram contains about 3.60 × 1021 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains erbium with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.