Atomic number 68 · Lanthanide
Erbium Er
Erbium (Er), element 68, is a silvery-white lanthanide metal. Erbium-doped fibre amplifiers boost light signals directly inside optical fibres, and they are a quiet backbone of the undersea cables that carry the internet between continents.
Key properties
| Atomic number | 68 |
|---|---|
| Atomic weight | 167.26 (CIAAW 2024 abridged standard atomic weight) |
| Category | Lanthanide |
| Group | Lanthanides/actinides (no group number) |
| Period | 6 |
| Block | f |
| State (25 °C, 1 atm) | Solid |
| Melting point | 1802 K (1528.8 °C) |
| Boiling point | 3141 K (2867.8 °C) |
| Density | 9.07 g/cm³ |
| Electronegativity (Pauling) | 1.24 |
| Atomic radius (van der Waals) | 235 pm |
| First ionization energy | 6.108 eV |
| Electron affinity | — |
| Oxidation states | +3 |
| Discovered | 1843 |
Electron configuration
- Condensed
- [Xe]6s2 4f12
- Full
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f12 5s2 5p6 6s2
- Electrons per shell
- 2 · 8 · 18 · 30 · 8 · 2
Orbital diagram
Position in the table
Discovery
Erbium's story also begins with minerals from the Ytterby quarry in Sweden. In 1843 Carl Gustaf Mosander, while breaking down yttria, found two new oxides that he called erbia and terbia. The names were later swapped by other chemists, and the usual account is that today's erbia is the substance Mosander originally called by the other name.
Erbia itself proved to be a mixture: ytterbium was separated from it in 1878, and scandium, holmium and thulium in 1879. Reasonably pure erbium metal was first obtained in 1934 by Wilhelm Klemm and Heinrich Bommer, who reduced anhydrous erbium chloride with potassium vapour.
Origin of the name
Like yttrium, terbium and ytterbium, erbium is named after the village of Ytterby.
Main uses
- Optical amplifiers: erbium ions in a silica fibre, pumped by a laser, amplify light near 1.55 micrometres, the main telecom wavelength, without converting it to an electrical signal. This made long-haul fibre links and transoceanic cables far simpler.
- Medical and cosmetic lasers: Er:YAG lasers at about 2.94 micrometres are absorbed extremely strongly by water, allowing very shallow, precise ablation in skin resurfacing and dentistry.
- Pink colourant: erbium oxide gives glass, sunglasses and imitation gemstones a pink tint.
- Alloys: small additions improve the workability of vanadium and some other metals.
Isotopes
Natural erbium has six stable isotopes; erbium-166 is the most common at about a third of the total. Artificial erbium-169, with a half-life of about 9.4 days, emits soft beta radiation and is used to treat inflamed small joints such as finger joints.
In everyday life
When you stream a video from another continent, the light carrying it is amplified by erbium-doped fibre many times on its way across the ocean floor. Pink decorative glass may also owe its colour to erbium. Before these amplifiers were commercialised in the 1990s, fibre links needed repeaters that converted light to electricity and back; erbium amplifiers boost many wavelengths at once, which, combined with wavelength-division multiplexing, multiplied network capacity. The element has no known biological role and is considered to be of low toxicity.
Good to know
- Without erbium-doped fibre amplifiers, transoceanic internet cables would be far more complex and expensive.
- Erbium oxide is one of the few simple ways to give glass a soft pink colour.
- The substance first called erbia later yielded ytterbium, scandium, holmium and thulium.
Same category (Lanthanide)
Data sources · Properties: PubChem Periodic Table (US NIH/NLM public data) · Atomic weights: CIAAW 2024 abridged standard atomic weights · Names: Wikidata (CC0); Korean names follow the Korean Chemical Society. Retrieved 2026-09-23.