Holmium (Ho)

Holmium has the highest magnetic moment of any naturally occurring element, which is why it is used as the pole piece in research magnets that need every last tesla. Its absorption spectrum has a set of unusually sharp, stable peaks, so a holmium oxide filter is a standard reference for checking the wavelength calibration of a spectrophotometer. Holmium:YAG lasers at 2,100 nm are strongly absorbed by water, which makes them precise surgical tools — they cut tissue and shatter kidney stones with very little collateral heating.

Properties

Atomic number

67

Symbol

Ho

Standard atomic weight

164.93 u

Category

Lanthanide

Period

6

Block

f-block

Electron configuration

[Xe] 6s² 4f¹¹

Electrons per shell

2, 8, 18, 29, 8, 2

Melting point

1,747 K — 1473.8 °C — 2684.9 °F

Boiling point

2,973 K — 2699.8 °C — 4891.7 °F

Density

8.8 g/cm³

Electronegativity

1.23 (Pauling)

Oxidation states

+3

Discovered

1878 by Marc Delafontaine and Jacques-Louis Soret, and independently Per Teodor Cleve

Electron configuration

Full

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹¹

Noble gas shorthand

[Xe] 6s² 4f¹¹

Shells

K: 2 · L: 8 · M: 18 · N: 29 · O: 8 · P: 2

What it is used for

• Holmium:YAG surgical lasers for kidney stones and prostate surgery
• Pole pieces that concentrate the field in the strongest laboratory magnets
• Wavelength calibration standards for spectrophotometers
• Yellow and red glass and cubic zirconia colouring

Neighbours in the table