Erbium (Er)
Lanthanide
Erbium keeps the internet running: erbium-doped fibre amplifiers boost light signals directly inside optical fibres, letting data cross oceans without electronic relays. Its oxide also tints glass and gems pink.
Position on the periodic table
Atomic properties
| Atomic number | 68 |
|---|---|
| Atomic mass | 167.259 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f12 |
| Noble gas shorthand | [Xe] 4f12 6s2 |
| Electrons per shell | 2, 8, 18, 30, 8, 2 |
| Valence electrons (outer shell) | 2 |
| Common oxidation states | +3 |
| Electronegativity (Pauling) | 1.24 |
| Covalent radius (approx.) | 189 pm |
| First ionization energy | 589.3 kJ/mol |
| Electron affinity | 30.1 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 9.066 g/cm³ |
| Melting point | 1528.8 °C (1802 K) |
| Boiling point | 2867.8 °C (3141 K) |
| Appearance | silvery white |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of erbium
Erbium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f12, usually shortened to [Xe] 4f12 6s2. Its electrons occupy 6 shells (2, 8, 18, 30, 8, 2), placing it in period 6 of the f-block. Explore it interactively in the electron configuration calculator.
Uses of erbium
- Fibre-optic signal amplifiers
- Pink glass and cubic zirconia colouring
- Dermatology and dental lasers
- Vanadium alloy softener
Biological role: None known.
Occurrence: From monazite, xenotime and clays.
Common compounds of erbium
Er2O3
Erbium(III) oxide
History and discovery
Discovered: 1843 — Carl Gustaf Mosander. Name origin: Named after Ytterby, Sweden.
Carl Gustaf Mosander separated erbium from yttrium earth in 1843.
Safety notes
Low toxicity; typical rare-earth precautions.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Erbium
1. What is the chemical symbol of Erbium?
2. What is the atomic number of Erbium?
3. Which category does Erbium belong to?
4. What is the state of Erbium at room temperature?
5. Which period of the periodic table is Erbium in?
Erbium FAQs
What is the atomic number of erbium?
Erbium's atomic number is 68 — every erbium atom has 68 protons in its nucleus.
What is the symbol for erbium?
Er. Named after Ytterby, Sweden.
Is erbium a metal, nonmetal, or metalloid?
Erbium is classified as a lanthanide.
What state is erbium at room temperature?
At about 25 °C, erbium is a solid. It melts at 1528.8 °C.
What is erbium used for?
Key uses include: fibre-optic signal amplifiers; pink glass and cubic zirconia colouring; dermatology and dental lasers.
Related elements
Keep working with this element
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