Erbium (Er)
Element 68 · Lanthanide · atomic mass 167.26 u · f-block, period 6
Electron shells: 2, 8, 18, 30, 8, 2
Erbium amplifies light at exactly the wavelength fibre-optic cables use, which is why intercontinental internet works. Erbium-doped amplifiers boost signals without converting them to electricity.
Every transoceanic internet cable relies on erbium to re-boost the light every 50-100 km.
- Atomic number
- 68
- Atomic mass
- 167.26 u
- Electron configuration
- [Xe] 6s² 4f¹²
- Group · period · block
- f-block · 6 · f
- Oxidation states
- +3
- Electronegativity
- 1.24 (Pauling)
- Melting point
- 1,529 °C
- Boiling point
- 2,868 °C
- Density
- 9.07 g/cm³
- State at 20 °C
- Solid
- Appearance
- Silvery-white metal
- Discovered
- Carl Gustaf Mosander, 1843
68 protons, and 68 electrons when neutral
IUPAC standard atomic weight
Shown in the strip below the table
What Erbium is used for
- Erbium-doped fibre amplifiers
- Pink glass and gemstone colouring
- Dermatological and dental lasers
- Nuclear control rods
Atomic structure of Erbium
A neutral erbium atom has 68 protons and 68 electrons. Its most common isotope carries about 99 neutrons, which is where the mass number 167 comes from. Change the neutron count and you have a different isotope of erbium; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 18, 30, 8, 2. In orbital notation that is [Xe] 6s² 4f¹². As a f-block element its valence count is variable, which is why it can form compounds in several oxidation states.
3D electron orbitals
See where Erbium's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Erbium sits in the periodic table
Discovery and naming
Erbium was discovered by Carl Gustaf Mosander in 1843. Its name comes from Ytterby, a Swedish village.
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Erbium?
The standard atomic weight of Erbium is 167.26 u, as published by IUPAC's Commission on Isotopic Abundances and Atomic Weights.
How many protons, neutrons and electrons does Erbium have?
Erbium has 68 protons, because the atomic number is the proton count and that is what makes an atom Erbium at all. A neutral Erbium atom has the same number of electrons, 68. The neutron count varies by isotope; the most common one has about 99, since 167 − 68 = 99.
What is the electron configuration of Erbium?
The electron configuration of Erbium is [Xe] 6s² 4f¹². Its electrons are arranged 2, 8, 18, 30, 8, 2 across 6 shells.
Is Erbium a metal?
Yes. Erbium is classified as a lanthanide, on the metallic side of the table.
What group and period is Erbium in?
Erbium sits in the f-block strip below the main table, in period 6, among the lanthanides. Elements in that strip are not given a group number in the standard 18-column layout.
What is the charge of Erbium?
Erbium most commonly forms a 3+ ion. Like most transition metals it has several accessible oxidation states, so the charge depends on the compound.
What is the melting point of Erbium?
Erbium melts at 1,529 °C and boils at 2,868 °C. That puts it in the solids at everyday temperatures.
What is Erbium used for?
Erbium-doped fibre amplifiers, Pink glass and gemstone colouring, Dermatological and dental lasers, Nuclear control rods. Erbium amplifies light at exactly the wavelength fibre-optic cables use, which is why intercontinental internet works.
Who discovered Erbium, and where does its name come from?
Erbium (Er) was discovered by Carl Gustaf Mosander in 1843. The name comes from Ytterby, a Swedish village.