Write the formula for ruthenium(III) chloride, the common starting salt.
Ru3+ with three Cl-: RuCl3. Nearly all ruthenium lab chemistry — catalysts, dyes, electrode preparations — begins from this dark-brown solid.
What Is the Charge of Ruthenium?
Ruthenium commonly forms Ru3+ Ru4+ in introductory ionic compounds.
Ruthenium's common states are +3 (RuCl3, the standard lab entry point) and +4 (RuO2, an electrode coating). It is a platinum-group metal whose full range runs remarkably wide — up to +8 in RuO4, one of the few compounds where any element reaches that state.
| Element | Ruthenium |
|---|---|
| Symbol | Ru |
| Atomic number | 44 |
| Common ionic charge | +3, +4 |
| Common ions | Ru3+, Ru4+ |
Visual reference
Ruthenium element image and atomic model
Images are used as visual references; charge rules still depend on the compound.
Where Ruthenium's charge options come from
Ruthenium is [Kr]4d7 5s1. Its many d electrons and middling electronegativity open an unusually broad ladder of oxidation states (-2 to +8, the widest span known alongside osmium). For everyday purposes, though, the +3/+4 pair covers its chemistry.
This is a classroom reference range, not an exhaustive list of all oxidation states.
The trap in Ruthenium problems
Treating RuO4 like the familiar dioxide. Ruthenium tetroxide (+8) is volatile, toxic, and aggressive — used in trace-lab work to stain fingerprints and cross-section polymers. The +4 dioxide is a tame electrode material. Twenty-six electrons of difference in formula, worlds apart in behavior.
Worked example: Ru in a formula problem
Ru3+ and Ru4+ in real compounds
RuCl3
Ruthenium chloride
Ru3+ balances chloride ions.
Ru2O3
Ruthenium oxide
Ruthenium can form oxides where total positive and negative charge balances.
Questions students ask about ruthenium
Where does ruthenium's charge matter in real technology?
RuO2 (+4) coats the titanium anodes that make chlorine industrially — the 'dimensionally stable anode' that quietly replaced graphite worldwide. Hard drives also layer neutral ruthenium atoms nanometers thick.
What were ruthenium dyes doing in solar cells?
Dye-sensitized ('Grätzel') cells used Ru2+ complexes whose excited electrons inject into titanium dioxide. The ruthenium cycles 2+/3+ every time a photon lands — charge change as the engine of the device.
Is ruthenium related to platinum?
It is one of the six platinum-group metals — dense, rare, catalytic. Like platinum it often works at charge 0 as a metal catalyst, with its ionic states (+3/+4) reserved for solution chemistry.
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.