Holmium (Ho)
Element 67 · Lanthanide · atomic mass 164.93 u · f-block, period 6
Electron shells: 2, 8, 18, 29, 8, 2
Holmium has the highest magnetic moment of any naturally occurring element. Holmium lasers are the standard tool for shattering kidney stones and treating prostates.
The laser most urologists reach for to break up kidney stones is a holmium laser.
- Atomic number
- 67
- Atomic mass
- 164.93 u
- Electron configuration
- [Xe] 6s² 4f¹¹
- Group · period · block
- f-block · 6 · f
- Oxidation states
- +3
- Electronegativity
- 1.23 (Pauling)
- Melting point
- 1,474 °C
- Boiling point
- 2,700 °C
- Density
- 8.8 g/cm³
- State at 20 °C
- Solid
- Appearance
- Silvery-white metal
- Discovered
- Marc Delafontaine and Jacques-Louis Soret, 1878
67 protons, and 67 electrons when neutral
IUPAC standard atomic weight
Shown in the strip below the table
What Holmium is used for
- Surgical lasers for kidney stones
- Magnetic flux concentrators
- Nuclear control rods
- Yellow-red glass colouring
Atomic structure of Holmium
A neutral holmium atom has 67 protons and 67 electrons. Its most common isotope carries about 98 neutrons, which is where the mass number 165 comes from. Change the neutron count and you have a different isotope of holmium; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 18, 29, 8, 2. In orbital notation that is [Xe] 6s² 4f¹¹. As a f-block element its valence count is variable, which is why it can form compounds in several oxidation states.
3D electron orbitals
See where Holmium's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Holmium sits in the periodic table
The first f-block row, elements 57-71. Chemically near-identical to each other and hard to separate, yet essential to magnets, lasers and phosphors.
- One proton lighter: Dysprosium.
- One proton heavier: Erbium.
Discovery and naming
Holmium was discovered by Marc Delafontaine and Jacques-Louis Soret in 1878. Its name comes from Latin Holmia, "Stockholm".
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Holmium?
The standard atomic weight of Holmium is 164.93 u, as published by IUPAC's Commission on Isotopic Abundances and Atomic Weights.
How many protons, neutrons and electrons does Holmium have?
Holmium has 67 protons, because the atomic number is the proton count and that is what makes an atom Holmium at all. A neutral Holmium atom has the same number of electrons, 67. The neutron count varies by isotope; the most common one has about 98, since 165 − 67 = 98.
What is the electron configuration of Holmium?
The electron configuration of Holmium is [Xe] 6s² 4f¹¹. Its electrons are arranged 2, 8, 18, 29, 8, 2 across 6 shells.
Is Holmium a metal?
Yes. Holmium is classified as a lanthanide, on the metallic side of the table.
What group and period is Holmium in?
Holmium sits in the f-block strip below the main table, in period 6, among the lanthanides. Elements in that strip are not given a group number in the standard 18-column layout.
What is the charge of Holmium?
Holmium most commonly forms a 3+ ion. Like most transition metals it has several accessible oxidation states, so the charge depends on the compound.
What is the melting point of Holmium?
Holmium melts at 1,474 °C and boils at 2,700 °C. That puts it in the solids at everyday temperatures.
What is Holmium used for?
Surgical lasers for kidney stones, Magnetic flux concentrators, Nuclear control rods, Yellow-red glass colouring. Holmium has the highest magnetic moment of any naturally occurring element.
Who discovered Holmium, and where does its name come from?
Holmium (Ho) was discovered by Marc Delafontaine and Jacques-Louis Soret in 1878. The name comes from Latin Holmia, "Stockholm".