Periodic Table of Elements




Holmium was discovered by Marc Delafontaine and Jacques-Louis Soret in 1878 in Switzerland. Later in 1878, a Swedish chemist, Per Teodor Cleve independently discovered the element while he was working on erbia earth (erbium oxide).

Name: Holmium
Symbol: Ho
Atomic number: 67
Atomic weight: 164.93
State: solid
Group, period, block: n/a, 6, f
Color: silvery white
Classification: lanthanide
Electron configuration: 4f11 6s2

Physical properties

Density: 8.79 g/cm-3
Melting point: 1734 K,1461 C,2662 F
Boiling point: 2993 K,2720 C,4928 F

Atomic properties

Oxidation states: 3, 2, 1
Electronegativity: 1.23 (Pauling scale)
Ionization energies: 1st: 581.0 kJmol-1
Covalent radius: 1927 pm
Van der Waals radius: no data
  • Ho
  • Electron Configuration


There is one naturally occurring isotope of holmium exists, 165Ho.