Protactinium - Wikiparency

# Protactinium ## 🧊 Protactinium · 3D (three.js) <iframe src="https://wikitube-elements.netlify.app/?el=Pa&embed=1" width="100%" height="620" frameborder="0" style="border:0;border-radius:12px;overflow:hidden" allowfullscreen loading="lazy" title="The Elements 3D microsim - Protactinium"></iframe> *Protactinium in the live three.js Elements explorer — drag to orbit the atom, click any tile to compare, slide the temperature.* · [▶ open full](https://wikitube-elements.netlify.app/?el=Pa)  !Protactinium plate.svg *Plate 91 of 118 - animated Bohr shells, stylized per Madelung filling; engraving style per house Arcanity kit.* ## Microsim To Do *Claimable rows, house pattern. Real Wikipedia articles only.* - [[Decay_chain|Decay chain]] - protactinium-231 in the uranium-235 series - [[Half-life|Half-life]] - protactinium-231 at 32,760 years and isotope abundance - Uranium-235 - source of protactinium in nuclear fuel cycles - [[Actinium|Actinium]] - protactinium-231 decays to actinium-227 ## Links (Wikipedia order)  `Acid` · `Acta_Crystallographica` · `Actinide` · `Actinide_concept` · [[Actinium]] · `Actinium-225` · `Alkali_metal` · `Alkaline_earth_metal` · [[Alpha_decay]] · [[Alpha_particle]] · [[Aluminium]] · `Aluminium_bromide` · [[Americium]] · `Angewandte_Chemie` · [[Antimony]] · [[Argon]] · `Aristid_von_Grosse` · [[Arsenic]] · [[Astatine]] · `Atomic_number` · `Atomic_radius` · [[Barium]] · `Basic_oxide` · `Becquerel` · `Bentonite` · [[Berkelium]] · [[Beryllium]] · [[Beta_decay]] · `Beta_particle` · [[Bismuth]] · `Block_(periodic_table)` · [[Bohrium]] · [[Boiling_point]] · `Borohydride` · [[Boron]] · `Boron_group` · `Bromide` · [[Bromine]] · 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Infobox grounded in [Wikipedia: List of chemical elements](https://en.wikipedia.org/wiki/List_of_chemical_elements), fetched 2026-07-08. Full article: [Wikipedia: Protactinium](https://en.wikipedia.org/wiki/Protactinium).  ## Key facts (infobox) | | | |---|---| | Symbol - Z | Pa - 91 | | Group - Period - Block | f - 7 - f-block | | Atomic weight (Da) | 231.04 | | Density (g/cm3) | 15.37 | | Melting - Boiling (K) | 1841 - 4300 | | Electronegativity (Pauling) | 1.5 | | Crustal abundance (mg/kg) | 1.4e-6 | | Origin | from decay | | Phase (STP) | solid | | Name origin | proto- + actinium: it decays into actinium | *Bracketed weights are the mass number of the most stable isotope; values in parentheses are predictions (per the source table).* ## Story Protactinium was discovered in 1917 independently by Kasimir Fajans and Oswald Helmuth Göhring (working with Otto Hahn). It is a rare decay product of uranium-235 in the actinium decay chain, appearing as protactinium-231 with a half-life of 32,760 years. [model-prior - verify] The element's name reflects its position: *proto-* (meaning "first" or "parent") and *actinium*, because it decays into actinium-227. It is one of the rarest naturally occurring elements. Protactinium is a dense, silvery, and highly toxic actinide metal. Its extreme rarity and short half-life (in practical terms) make it difficult to study and isolate. It has no known commercial applications. Most protactinium in existence is produced in nuclear reactors as a byproduct of uranium processing. Because of its scarcity and hazard profile, it remains a laboratory curiosity and research specimen only. In the canon, protactinium represents the bridge between the well-known actinium decay chain and uranium itself. It is a decay intermediate that underscores the complexity of heavy-element nuclear chemistry and the richness of decay pathways. ## Corpus connections Protactinium is a decay intermediate in the uranium-235 actinium series, connecting the light actinides to uranium itself and exemplifying the richness of decay chains. - R.E.A.C.T.I.O.N. - the Chemistry hub - Centers of Excellence Portal - [[Technetium|Technetium - the element made before found]] - the canon's patron - and Technitium, the School - [Uranium-235 decay chain](https://en.wikipedia.org/wiki/Decay_chain) - protactinium-231 is a key intermediate - [Actinium decay series](https://en.wikipedia.org/wiki/Decay_chain) - protactinium-231 decays to actinium-227 ## Vocational-Technical Semiotics The element speaks the canon's shared signs: the periodic table cell (Pa, group f, period 7), isotope notation, and hazard pictograms ghs where handling demands it. ## Sources Infobox: [en.wikipedia.org/wiki/List_of_chemical_elements](https://en.wikipedia.org/wiki/List_of_chemical_elements) (fetched 2026-07-08); etymology per the same table's notes. Story sources to be added at enrichment. ## Navigation - Canon: Elements Canon index - neighbors by Z: [[Thorium|Thorium (90)]] - [[Uranium|Uranium (92)]] - R.E.A.C.T.I.O.N. - Centers of Excellence ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Protactinium) : [Wikitube](https://en.wikitube.io/wiki/Protactinium) ## Previous hub tags Tree parents: [[Helium]] · [[Hydrogen]] · [[Oxygen]]. Legacy hubs: none. --- *Sources: 1 legacy note. Minted wave 1, 2026-07-30 (v1.6 order).*