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Erbium

Element 68 · Lanthanide

Specimen

Atomic number
68
Atomic mass
167.26
State at room temperature
Solid
Melting point
1,529 °C
Boiling point
2,868 °C
Density
9.07 g/cm³
Discovered
1843

Physical data from PubChem.1

Can I eat it?

In food and water
Not needed, little harm known. Erbium has no known function in the body. In a rat test, 6.2 g of erbium chloride per kg of body weight killed half the animals. The RSC lists it as low in toxicity. There are few studies of it in food. 23

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The atom

Er
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 30
5 (O) 8
6 (P) outermost 2
Total68

Configuration [Xe] 4f¹² 6s²

4f ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↑
6s ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 68 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Xe core, with one arrow per electron.

Related elements

Lanthanides
La Lanthanum Ce Cerium Pr Praseodymium Nd Neodymium Pm Promethium Sm Samarium Eu Europium Gd Gadolinium Tb Terbium Dy Dysprosium Ho Holmium Tm Thulium Yb Ytterbium Lu Lutetium

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Sources

  1. 1

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Atomic mass, electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  2. 2

    Toxicology Excellence for Risk Assessment (TERA), for the US Bureau of Land Management, 1999. Development of Reference Doses and Reference Concentrations for Lanthanides , Section 2.4 (oral toxicity data in experimental animals).

    • 6200 for erbium chloride
  3. 3

    Royal Society of Chemistry, 2026. Erbium - Element information, properties and uses .

    • Erbium has no known biological role, and has low toxicity.