Holmium (Ho)

Holmium is a chemical element with symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a rare-earth element.

Atomic Number

67

Atomic Mass

164.93 u

Category

lanthanide

Phase

solid

Density

8.8 g/cm³

Electron Shells

2, 8, 18, 29, 8, 2

Atomic Structure

Protons: 67 • Electrons: 67 • Neutrons: Varies by isotope

Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹¹

Discovery

1878 • Per Teodor Cleve, Jacques-Louis Soret, Marc Delafontaine