68167.26ErErbium
Erbium (Er) — element 68lanthanide · period 6
Erbium is a chemical element with the symbol Er and atomic number 68. It is a lanthanide in period 6 of the periodic table (the f-block), with a standard atomic mass of 167.26 u. At room temperature (25 °C) erbium is a solid.
💡 Known for: Erbium-doped fibre amplifiers boost the light signals in fibre-optic internet cables.
# Erbium properties
| Symbol | Er |
|---|---|
| Atomic number | 68 |
| Atomic mass | 167.26 u |
| Category | lanthanide |
| Group | — (f-block, no group number) |
| Period | 6 |
| Block | f-block |
| Electron configuration | [Xe] 4f¹² 6s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹² 5s² 5p⁶ 6s² |
| Electrons per shell | 2, 8, 18, 30, 8, 2 |
| Protons / electrons | 68 / 68 |
| State at 25 °C | solid |
| Melting point | 1802 K (1528.8 °C, 2783.9 °F) |
| Boiling point | 3141 K (2867.8 °C, 5194.1 °F) |
| Density | 9.066 g/cm³ |
| Electronegativity (Pauling) | 1.24 |
| First ionization energy | 6.108 eV |
| Atomic radius | 226 pm |
| Discovered | 1842 |
# Electron configuration of erbium
The electron configuration of erbium is [Xe] 4f¹² 6s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹² 5s² 5p⁶ 6s². Its 68 electrons fill 6 shells as 2, 8, 18, 30, 8, 2, so the outermost shell holds 2 electrons.
# Related elements
HoHolmiumprevious elementTmThuliumnext elementLaLanthanumlanthanideCeCeriumlanthanidePrPraseodymiumlanthanideNdNeodymiumlanthanidePmPromethiumlanthanideSmSamariumlanthanideEuEuropiumlanthanideGdGadoliniumlanthanide
# Erbium FAQ
What is the atomic number of erbium?
The atomic number of erbium is 68: every erbium atom has 68 protons in its nucleus. Its symbol is Er.
What is the atomic mass of erbium?
The standard atomic mass of erbium is 167.26 u.
What is the electron configuration of erbium?
Erbium's electron configuration is [Xe] 4f¹² 6s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹² 5s² 5p⁶ 6s²), with 2, 8, 18, 30, 8, 2 electrons per shell.
Is erbium a metal?
Yes. Erbium is a lanthanide, one of the metals.
What is the melting point of erbium?
Erbium melts at 1802 K (1528.8 °C, 2783.9 °F) and boils at 3141 K (2867.8 °C, 5194.1 °F).
What is erbium used for / known for?
Erbium-doped fibre amplifiers boost the light signals in fibre-optic internet cables.