Trihydrogen cation
chemical compound
The trihydrogen cation or protonated molecular hydrogen (IUPAC name: hydrogenonium ion) is a cation (positive ion) with formula H+3, consisting of three hydrogen nuclei (protons) sharing two electrons.
The trihydrogen cation is one of the most abundant ions in the universe. It is stable in the interstellar medium (ISM) due to the low temperature and low density of interstellar space. The role that H+3 plays in the gas-phase chemistry of the ISM is unparalleled by any other polyatomic ion.
The trihydrogen cation is the simplest triatomic molecule, because its two electrons are the only valence electrons in the system. It is also the simplest example of a three-center two-electron bond system.
History
H+3 was first discovered by J. J. Thomson in 1911. While using an early form of mass spectrometry to study the resultant species of plasma discharges, he discovered a large abundance of a polyatomic ion with a mass-to-charge ratio of 3. He stated that the only two possibilities were C4+ or H+3. Since the signal grew stronger in pure hydrogen gas, he correctly assigned the species as H+3.
“Trihydrogen cation” enters the record as chemical compound. Crown Archives preserves that source wording while asking what Trihydrogen, cation and chemical can confirm, complicate or overturn.
Why this record matters
“Trihydrogen cation” is worth following because a concise public description often conceals a longer documentary argument. Here, Trihydrogen, cation and chemical provides the most credible route into that argument.
The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Sep 6, 2026. The linked authority identifier is Q2345425. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1911.
A general summary may omit uncertainty, sample limits or methodological disagreement that is explicit in the technical record. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Check terminology, classification and the date of the cited evidence. Scientific names and technical consensus can change while older records retain historical value.
- Current terminology
- Classification context
- Finding cited technical literature
Primary datasets, specimen catalogues, standards bodies and the most recent peer-reviewed literature.
Three-step research path
- Establish the record: confirm the title “Trihydrogen cation”, its source revision and the description used here.
- Expand the search: follow Trihydrogen cation primary sources, Trihydrogen cation archive and Trihydrogen research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Trihydrogen cation”?
- Which observation, specimen, dataset or publication supports the account?
- Has classification or technical consensus changed since the cited source?
Search terms from this dossier
This entry incorporates text from “Trihydrogen cation” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.