Write the formula for holmium(III) oxide, used to calibrate spectrophotometers.
Ho3+ with O2- gives Ho2O3. Its solution's sharp absorption peaks are so reproducible that agencies certify holmium oxide filters as wavelength standards.
What Is the Charge of Holmium?
Holmium commonly forms Ho3+ in introductory ionic compounds.
Holmium is Ho3+ — pink-yellow salts like HoCl3, oxide Ho2O3 — and holds a record: the highest magnetic moment of any naturally occurring element's ion. Surgeons know it from the holmium laser that pulverizes kidney stones.
| Element | Holmium |
|---|---|
| Symbol | Ho |
| Atomic number | 67 |
| Common ionic charge | +3 |
| Common ions | Ho3+ |
Visual reference
Holmium element image and atomic model
Images are used as visual references; charge rules still depend on the compound.
The electron story behind Holmium's charge
Holmium is [Xe]4f11 6s2; losing three electrons gives Ho3+ (f10) with four unpaired f electrons arranged for maximum total moment. As with its neighbors, no alternative charge offers any shell-stability bribe, so +3 stands alone.
This is a classroom reference range, not an exhaustive list of all oxidation states.
The assumption that trips people up on Holmium
Expecting the 'record magnetism' to make holmium compounds behave strangely on the bench. Ho3+ dissolves, precipitates, and crystallizes exactly like any mid-lanthanide; the magnetism shows up only in magnetometers and cryogenic devices.
Worked example: Ho in a formula problem
Ho3+ in real compounds
HoCl3
Holmium chloride
Ho3+ balances chloride ions.
Ho2O3
Holmium oxide
Holmium can form oxides where total positive and negative charge balances.
Questions students ask about holmium
Why do urologists use a holmium laser?
Ho3+ doped into YAG lases at 2.1 µm — a wavelength water absorbs strongly, so the energy dumps precisely where the fiber points, shattering stones with minimal collateral heating.
What are holmium pole pieces?
Slugs of neutral holmium metal placed in magnet gaps to concentrate flux — its atoms' huge moments squeeze fields higher than iron can. Charge 0; the f electrons do the work.
Did holmium star in quantum computing news?
Single holmium atoms on surfaces have stored a magnetic bit stably — one atom, one bit. Research-stage, but it showcases how much magnetic information one f10 ion's worth of electrons can hold.
How do I use this charge in formulas?
Combine positive and negative ions so the total charge is zero — or let the ionic compound calculator do the crossing for you. The full chart lives on the periodic table with charges.
Where this data comes from
Charges and element facts on this page are checked against the primary references below. Found an error? Email hello@periodictablewithcharges.com — corrections ship in the next content update. See how this site is edited.