Francium commonly forms Fr+ in introductory ionic compounds.
| Element | Francium |
|---|---|
| Symbol | Fr |
| Atomic number | 87 |
| Common ionic charge | +1 |
| Common ions | Fr+ |
Images are used as visual references; charge rules still depend on the compound.
Francium is [Rn]7s1: one electron over a radon core, the alkali-metal signature. Intriguingly, relativistic contraction tightens that 7s electron so much that francium's ionization energy is slightly higher than cesium's — the reactivity trend bends at the bottom of the table, though the +1 chemistry is unchanged.
Repeating 'francium is the most reactive metal' from older textbooks. Measured atom-by-atom, cesium likely out-reacts it — relativity claws back some of francium's expected eagerness. The +1 charge is certain; the superlative is not.
Fr+ with Cl-: FrCl — never synthesized in weighable form, but as certain as group membership can make a prediction. Magneto-optical traps holding a few thousand francium atoms confirm alkali behavior.
Francium chloride
Fr+ balances chloride ions.
Francium oxide
Francium can form oxides where total positive and negative charge balances.
Nothing you could watch — decay heat would vaporize any macroscopic lump instantly, before its famous water reaction had a chance. The thought experiment is more chemistry-lore than physics.
Its heavy, simple one-electron structure amplifies subtle nuclear-physics effects (parity violation). A few thousand trapped Fr atoms serve as a tabletop particle-physics lab — the +1 ion's parent atom as instrument.
Yes — Marguerite Perey, 1939, from actinium decay. Every element found since has been man-made; francium closed the book on nature's own inventory.
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.
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