Erbium (Er): Electron Configuration, Properties and Uses
Erbium (Er): Electron Configuration, Properties and Uses
Electron configuration [Xe] 6s2 4f12 · f-block, lanthanide series · period 6 · Ar 167.26
Erbium data
- Atomic number
- 68
- Relative atomic mass
- 167.26
- Group
- – (lanthanide series)
- Period
- 6
- Block
- f
- Category
- Lanthanide
- Electron configuration
- [Xe] 6s2 4f12
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f12
- Electrons per shell
- 2, 8, 18, 30, 8, 2 (K L M N O P)
- Valence electrons
- 2 (in the outer shell)
- Electronegativity (Pauling)
- 1.24
- First ionisation energy
- 6.108 eV
- Atomic radius (van der Waals)
- 235 pm
- State at room temperature
- Solid
- Melting point
- 1529 °C
- Boiling point
- 2868 °C
- Density
- 9.07 g/cm³
- Common oxidation states
- +3
- Discovered
- 1843
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 8 · M 18 · N 30 · O 8 · P 2
Orbital diagram (outer electrons)
About erbium
Erbium, symbol Er, is element number 68 in the periodic table. It belongs to the lanthanide series in period 6 (f-block), usually shown below the main table. Erbium was first discovered in 1843. Erbium is a solid at room temperature, melting at 1529 °C and boiling at 2868 °C.
Erbium electron configuration
The electron configuration of erbium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f12, or in short [Xe] 6s2 4f12. Its electrons occupy 6 shells: K = 2, L = 8, M = 18, N = 30, O = 8, P = 2. As a lanthanide, erbium fills the 4f subshell. Its outer 6s subshell holds 2 electrons; valence electrons for this series are not assigned by the usual group rule. When it forms cations, electrons leave the outermost subshell first: Er3+ = [Xe] 4f11.
Filling order: 1s2(2) → 2s2(4) → 2p6(10) → 3s2(12) → 3p6(18) → 4s2(20) → 3d10(30) → 4p6(36) → 5s2(38) → 4d10(48) → 5p6(54) → 6s2(56) → 4f12(68)
Uses of erbium
Well-known applications of erbium include erbium-doped fibre amplifiers (EDFA) for long-distance internet links, skin and dental lasers, and pink glass colouring.
Safety
Erbium metal is generally safe to handle, but avoid breathing its dust and read the SDS before using Erbium compounds. Always read the safety data sheet (SDS) before working with a chemical.
Other lanthanides
Frequently asked questions
What is the electron configuration of erbium?
The electron configuration of erbium (Er, atomic number 68) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f12, or [Xe] 6s2 4f12 in short. By shell: 2, 8, 18, 30, 8, 2.
How many valence electrons does erbium have?
Erbium has 2 electrons in its outer shell. For lanthanides and actinides, valence electrons are not assigned by the usual group rule.
Which group and period is erbium in?
Erbium is in the lanthanide series, period 6, f-block.
What is the atomic mass of erbium?
The relative atomic mass of erbium is 167.26. Use it to calculate molar mass with the molar mass calculator.
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