Confirm rhenium's oxidation state in ammonium perrhenate, NH4ReO4.
NH4+ contributes +1; four O give -8; so Re = +7. This salt is the standard traded form of rhenium, later reduced to charge-0 metal for jet-engine superalloys.
What Is the Charge of Rhenium?
Rhenium commonly forms Re4+ Re7+ in introductory ionic compounds.
Rhenium — one of Earth's rarest stable elements — favors +7 in perrhenate (ReO4-) and Re2O7, with +4 in ReO2 and ReS2. It was the last stable element ever discovered (1925), and manganese's group predicts its chemistry almost perfectly.
| Element | Rhenium |
|---|---|
| Symbol | Re |
| Atomic number | 75 |
| Common ionic charge | +4, +7 |
| Common ions | Re4+, Re7+ |
Visual reference
Rhenium element image and atomic model
Images are used as visual references; charge rules still depend on the compound.
Where Rhenium's charge options come from
Rhenium is [Xe]4f14 5d5 6s2. Like manganese and technetium above it, the group maximum +7 engages all valence electrons — but two rows down, that top state has mellowed: perrhenate is a placid ion where permanganate is a firebrand. Same charge, tamer temperament.
This is a classroom reference range, not an exhaustive list of all oxidation states.
The trap in Rhenium problems
Expecting ReO4- to bleach and oxidize like MnO4-. Descending group 7 stabilizes the +7 state dramatically; perrhenate solutions are colorless and gentle enough for medical use. Charge number alone never tells the reactivity story.
Worked example: Re in a formula problem
Re4+ and Re7+ in real compounds
ReCl4
Rhenium chloride
Re4+ balances chloride ions.
Re2O3
Rhenium oxide
Rhenium can form oxides where total positive and negative charge balances.
Questions students ask about rhenium
Why do jet engines pay fortunes for rhenium?
A few percent of neutral Re atoms in nickel superalloy turbine blades blocks the creep that would slowly stretch blades at 1,600 °C. Six percent of a blade can be rhenium — charge 0, value immense.
What is ReS2 doing in 2D-materials labs?
Like MoS2 it forms atom-thin sheets (Re at +4), but with unusual in-plane anisotropy — electrons flow differently along different directions of the same sheet.
Does rhenium mirror technetium medically?
Closely: Re-186/188 perrhenate chemistry piggybacks on Tc-99m's, delivering therapeutic beta doses with the same +7-to-lower-state coordination tricks. Group chemistry as a drug-design shortcut.
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.