Francium - Wikiparency

# Francium ## 🧊 Francium · 3D (three.js) <iframe src="https://wikitube-elements.netlify.app/?el=Fr&embed=1" width="100%" height="620" frameborder="0" style="border:0;border-radius:12px;overflow:hidden" allowfullscreen loading="lazy" title="The Elements 3D microsim - Francium"></iframe> *Francium 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=Fr)  !Francium plate.svg *Plate 87 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.* - Alkali metal - francium as the heaviest and most chemically reactive member - Rarest elements - francium's sub-gram cosmic abundance - [[Radioactive_decay|Radioactive decay]] - francium-223 from actinium decay - Spectroscopy - detecting francium through atomic spectra ## Links (Wikipedia order)  `Abundance_of_the_chemical_elements` · [[Actinium]] · `Actinium-225` · `Albert_Ghiorso` · `Alkali_metal` · `Alkaline_earth_metal` · [[Alpha_decay]] · [[Aluminium]] · [[Americium]] · [[Antimony]] · [[Argon]] · [[Arsenic]] · [[Astatine]] · `Atom` · [[Atomic_mass]] · `Atomic_number` · [[Barium]] · `Barium_sulfate` · [[Berkelium]] · [[Beryllium]] · [[Beta_decay]] · [[Bismuth]] · `Block_(periodic_table)` · [[Bohrium]] · [[Boron]] · `Boron_group` · [[Bromine]] · `Brookhaven_National_Laboratory` · `Bulk_modulus` · `CAS_Registry_Number` · `CERN` · `CP_violation` · [[Cadmium]] · [[Caesium]] · `Caesium_perchlorate` · [[Calcium]] · [[Californium]] · `Cancer` · [[Carbon]] · 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[[Thallium]] · [[Thorium]] · [[Thulium]] · `Time_(magazine)` · `Timeline_of_chemical_element_discoveries` · [[Tin]] · [[Titanium]] · `Trace_radioisotope` · [[Tungsten]] · `Ullmann's_Encyclopedia_of_Industrial_Chemistry` · `University_of_California,_Berkeley` · `Ununennium` · `Uraninite` · [[Uranium]] · `Uranium-235` · `Valence_electron` · `Van_der_Waals_radius` · [[Vanadium]] · `Vapor_pressure` · `Virginia` · [[Wayback_Machine]] · `World_War_I` · `X-ray` · [[Xenon]] · [[Ytterbium]] · [[Yttrium]] · `Yvette_Cauchois` · [[Zinc]] · [[Zirconium]] > **Official MAIN - Chemical element, Z = 87.** Part of the Elements Canon (one canonical page per element). Infobox grounded in [Wikipedia: List of chemical elements](https://en.wikipedia.org/wiki/List_of_chemical_elements), fetched 2026-07-08. Full article: [Wikipedia: Francium](https://en.wikipedia.org/wiki/Francium).  ## Key facts (infobox) | | | |---|---| | Symbol - Z | Fr - 87 | | Group - Period - Block | 1 - 7 - s-block | | Atomic weight (Da) | [223] | | Density (g/cm3) | (2.48) | | Melting - Boiling (K) | 281 - 890 | | Electronegativity (Pauling) | >0.79 | | Crustal abundance (mg/kg) | ~1e-18 | | Origin | from decay | | Phase (STP) | unknown | | Name origin | France, homeland of discoverer Marguerite Perey | *Bracketed weights are the mass number of the most stable isotope; values in parentheses are predictions (per the source table).* ## Story Francium was discovered in 1939 by Marguerite Perey at the Curie Institute in Paris. She was working with actinium-227 and detected the short-lived francium-223 isotope as a decay product. Perey named the element after her country, France, and in doing so became the first woman to discover an element. Francium is extraordinarily rare and unstable; all isotopes are radioactive, and no single location contains more than a few grams of it at any moment. [model-prior - verify] Francium is an alkali metal, the heaviest known member of group 1. It is so rare and reactive that its standard chemistry could not be studied until many decades after its discovery. As an alkali metal, it exhibits extreme chemical reactivity and would spontaneously ignite in air or water. Francium has no practical applications due to its scarcity and instability, and most knowledge of its properties comes from spectroscopy and theoretical extrapolation from its lighter congeners. In the Elements Canon, francium marks a threshold: the entry into the unstable region where nearly all isotopes are short-lived and the element itself is more a theoretical construct than a substance. It embodies both the Curie legacy (discovered at the institute bearing their name) and the frontier of nuclear chemistry. ## Corpus connections Francium is the heaviest alkali metal and the rarest naturally occurring element. Discovered at the Curie Institute, it extends the Curie legacy into the unstable realm. - 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 - [Marguerite Perey](https://en.wikipedia.org/wiki/Marguerite_Perey) - first woman to discover an element - [Alkali metal](https://en.wikipedia.org/wiki/Alkali_metal) - francium as the heaviest and most reactive member ## Vocational-Technical Semiotics The element speaks the canon's shared signs: the periodic table cell (Fr, group 1, 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: [[Radon|Radon (86)]] - [[Radium|Radium (88)]] - R.E.A.C.T.I.O.N. - Centers of Excellence ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Francium) : [Wikitube](https://en.wikitube.io/wiki/Francium) ## Previous hub tags Tree parents: [[Helium]] · [[Hydrogen]] · [[Oxygen]]. Legacy hubs: none. --- *Sources: 1 legacy note. Minted wave 1, 2026-07-30 (v1.6 order).*